diff --git a/.scalafmt.conf b/.scalafmt.conf
index 8e4daf02..04974b20 100644
--- a/.scalafmt.conf
+++ b/.scalafmt.conf
@@ -2,7 +2,7 @@ version = 2.7.5
 
 docstrings = JavaDoc
 
-maxColumn = 120
+maxColumn = 100
 
 align = none
 align {
diff --git a/src/main/scala/aqua/Aqua.scala b/src/main/scala/aqua/Aqua.scala
index dccc6309..5ee36783 100644
--- a/src/main/scala/aqua/Aqua.scala
+++ b/src/main/scala/aqua/Aqua.scala
@@ -11,13 +11,15 @@ object Aqua {
   def parse(input: String): ValidatedNec[AquaError, Ast[Span.F]] =
     Ast.fromString[Span.F](input)
 
-  def validate(input: String): ValidatedNec[AquaError, Model] =
-    parse(input).andThen(ast => Semantics.validate(ast).leftMap(_.map(ts => CompilerError(ts._1.unit._1, ts._2))))
+  def generateModel(input: String): ValidatedNec[AquaError, Model] =
+    parse(input).andThen(ast =>
+      Semantics.generateModel(ast).leftMap(_.map(ts => CompilerError(ts._1.unit._1, ts._2)))
+    )
 
   def generate(input: String, air: Boolean): ValidatedNec[AquaError, String] =
-    validate(input).map {
-      case g: ScriptModel =>
-        if (air) g.generateAir else g.generateTypescript
+    generateModel(input).map {
+      case m: ScriptModel =>
+        if (air) m.generateAir else m.generateTypescript
       case _ => "//No input given"
     }
 
diff --git a/src/main/scala/aqua/model/FuncCallable.scala b/src/main/scala/aqua/model/FuncCallable.scala
index dc1f00f8..f9a56ea9 100644
--- a/src/main/scala/aqua/model/FuncCallable.scala
+++ b/src/main/scala/aqua/model/FuncCallable.scala
@@ -50,7 +50,8 @@ case class FuncCallable(
     // We have some names in scope (forbiddenNames), can't introduce them again; so find new names
     val shouldRename = findNewNames(forbiddenNames, treeDefines)
     // If there was a collision, rename exports and usages with new names
-    val treeRenamed = if (shouldRename.isEmpty) treeWithValues else treeWithValues.rename(shouldRename)
+    val treeRenamed =
+      if (shouldRename.isEmpty) treeWithValues else treeWithValues.rename(shouldRename)
 
     // Result could be derived from arguments, or renamed; take care about that
     val result = ret.map(_._1).map(_.resolveWith(argsToData)).map {
@@ -71,7 +72,9 @@ case class FuncCallable(
         case ((noNames, resolvedExports), CallArrowTag(None, fn, c)) if allArrows.contains(fn) =>
           // Apply arguments to a function – recursion
           val (appliedOp, value) =
-            allArrows(fn).apply(c.mapValues(_.resolveWith(resolvedExports)), argsToArrows, noNames).value
+            allArrows(fn)
+              .apply(c.mapValues(_.resolveWith(resolvedExports)), argsToArrows, noNames)
+              .value
 
           // Function defines new names inside its body – need to collect them
           // TODO: actually it's done and dropped – so keep and pass it instead
@@ -80,7 +83,10 @@ case class FuncCallable(
           (noNames ++ newNames, resolvedExports ++ c.exportTo.zip(value)) -> appliedOp.tree
         case (acc @ (_, resolvedExports), tag) =>
           // All the other tags are already resolved and need no substitution
-          acc -> Cofree[Chain, OpTag](tag.mapValues(_.resolveWith(resolvedExports)), Eval.now(Chain.empty))
+          acc -> Cofree[Chain, OpTag](
+            tag.mapValues(_.resolveWith(resolvedExports)),
+            Eval.now(Chain.empty)
+          )
       }
       .map { case ((_, resolvedExports), b) =>
         // If return value is affected by any of internal functions, resolve it
@@ -159,13 +165,7 @@ case class FuncCallable(
             ).value._1
           ) ++ Chain.fromSeq(returnCallback.toSeq)
       )
-      .resolveTopology(noop)
-
-  def noop(peerId: ValueModel): FuncOp =
-    FuncOp.wrap(
-      OnTag(peerId, Nil),
-      FuncOp.leaf(CallServiceTag(LiteralModel("\"op\""), "identity", Call(Nil, None), Some(peerId)))
-    )
+      .resolveTopology()
 
   def generateTsCall: Call =
     Call(
diff --git a/src/main/scala/aqua/model/FuncOp.scala b/src/main/scala/aqua/model/FuncOp.scala
index 3bf2c0ef..0447e955 100644
--- a/src/main/scala/aqua/model/FuncOp.scala
+++ b/src/main/scala/aqua/model/FuncOp.scala
@@ -1,6 +1,5 @@
 package aqua.model
 
-import aqua.model.FuncOp.wrap
 import cats.Eval
 import cats.data.Chain
 import cats.free.Cofree
@@ -16,8 +15,10 @@ case class FuncOp(tree: Cofree[Chain, OpTag]) extends Model {
     Cofree.cata(tree)(folder)
 
   def definesValueNames: Eval[Set[String]] = cata[Set[String]] {
-    case (CallArrowTag(_, _, Call(_, Some(export))), acc) => Eval.later(acc.foldLeft(Set(export))(_ ++ _))
-    case (CallServiceTag(_, _, Call(_, Some(export)), _), acc) => Eval.later(acc.foldLeft(Set(export))(_ ++ _))
+    case (CallArrowTag(_, _, Call(_, Some(export))), acc) =>
+      Eval.later(acc.foldLeft(Set(export))(_ ++ _))
+    case (CallServiceTag(_, _, Call(_, Some(export)), _), acc) =>
+      Eval.later(acc.foldLeft(Set(export))(_ ++ _))
     case (NextTag(export), acc) => Eval.later(acc.foldLeft(Set(export))(_ ++ _))
     case (_, acc) => Eval.later(acc.foldLeft(Set.empty[String])(_ ++ _))
   }
@@ -41,7 +42,7 @@ case class FuncOp(tree: Cofree[Chain, OpTag]) extends Model {
       )
     )
 
-  def resolveTopology(doVia: ValueModel => FuncOp): FuncOp =
+  def resolveTopology(): FuncOp =
     FuncOp(FuncOp.transformWithPath(tree) {
       case (path, c: CallServiceTag) =>
         Cofree[Chain, OpTag](
@@ -55,11 +56,12 @@ case class FuncOp(tree: Cofree[Chain, OpTag]) extends Model {
           OnTag(pid, Nil),
           Eval.now(
             Chain.fromSeq(
-              via.map(doVia).map(_.tree)
+              via.map(FuncOp.noop).map(_.tree)
             )
           )
         )
-      case (_, t) => Cofree[Chain, OpTag](t, Eval.now(Chain.empty))
+      case (_, t) =>
+        Cofree[Chain, OpTag](t, Eval.now(Chain.empty))
     })
 
   def :+:(prev: FuncOp): FuncOp =
@@ -68,14 +70,21 @@ case class FuncOp(tree: Cofree[Chain, OpTag]) extends Model {
 
 object FuncOp {
 
+  def noop(peerId: ValueModel): FuncOp =
+    FuncOp.wrap(
+      OnTag(peerId, Nil),
+      FuncOp.leaf(CallServiceTag(LiteralModel("\"op\""), "identity", Call(Nil, None), Some(peerId)))
+    )
+
   def traverseA[A](cf: Cofree[Chain, OpTag], init: A)(
     f: (A, OpTag) => (A, Cofree[Chain, OpTag])
   ): Eval[(A, Cofree[Chain, OpTag])] = {
     val (headA, head) = f(init, cf.head)
     // TODO: it should be in standard library, with some other types
     cf.tail
-      .map(_.foldLeft[(A, Chain[Cofree[Chain, OpTag]])]((headA, head.tailForced)) { case ((aggrA, aggrTail), child) =>
-        traverseA(child, aggrA)(f).value.map(aggrTail.append)
+      .map(_.foldLeft[(A, Chain[Cofree[Chain, OpTag]])]((headA, head.tailForced)) {
+        case ((aggrA, aggrTail), child) =>
+          traverseA(child, aggrA)(f).value.map(aggrTail.append)
       })
       .map(_.map(ch => head.copy(tail = Eval.now(ch))))
   }
@@ -83,13 +92,13 @@ object FuncOp {
   def transformWithPath(cf: Cofree[Chain, OpTag], path: List[OpTag] = Nil)(
     f: (List[OpTag], OpTag) => Cofree[Chain, OpTag]
   ): Cofree[Chain, OpTag] = {
-    val h = f(path, cf.head)
+    val newCf = f(path, cf.head)
     Cofree[Chain, OpTag](
-      h.head,
-      (h.tail, cf.tail)
+      newCf.head,
+      (newCf.tail, cf.tail)
         .mapN(_ ++ _)
         // IF make foldLeft here, will be possible to get info from prev sibling
-        .map(_.map(transformWithPath(_, h.head :: path)(f)))
+        .map(_.map(transformWithPath(_, newCf.head :: path)(f)))
     )
   }
 
diff --git a/src/main/scala/aqua/semantics/Semantics.scala b/src/main/scala/aqua/semantics/Semantics.scala
index 197f96c1..b4765c9f 100644
--- a/src/main/scala/aqua/semantics/Semantics.scala
+++ b/src/main/scala/aqua/semantics/Semantics.scala
@@ -4,7 +4,12 @@ import aqua.model.{FuncOp, Model}
 import aqua.parser.lexer.Token
 import aqua.parser.{Ast, Expr}
 import aqua.semantics.rules.ReportError
-import aqua.semantics.rules.abilities.{AbilitiesAlgebra, AbilitiesInterpreter, AbilitiesState, AbilityOp}
+import aqua.semantics.rules.abilities.{
+  AbilitiesAlgebra,
+  AbilitiesInterpreter,
+  AbilitiesState,
+  AbilityOp
+}
 import aqua.semantics.rules.names.{NameOp, NamesAlgebra, NamesInterpreter, NamesState}
 import aqua.semantics.rules.types.{TypeOp, TypesAlgebra, TypesInterpreter, TypesState}
 import cats.Eval
@@ -30,12 +35,13 @@ object Semantics {
         // TODO instead of foldRight, do slidingWindow for 2 elements, merge right associative ones
         // Then foldLeft just like now
         inners
-          .foldRight[Free[G, List[Model]]](Free.pure[G, List[Model]](List.empty[Model])) { case (a, b) =>
-            (a, b).mapN {
-              case (prev: FuncOp, (next: FuncOp) :: tail) if next.isRightAssoc =>
-                (prev :+: next) :: tail
-              case (prev, acc) => prev :: acc
-            }
+          .foldRight[Free[G, List[Model]]](Free.pure[G, List[Model]](List.empty[Model])) {
+            case (a, b) =>
+              (a, b).mapN {
+                case (prev: FuncOp, (next: FuncOp) :: tail) if next.isRightAssoc =>
+                  (prev :+: next) :: tail
+                case (prev, acc) => prev :: acc
+              }
           }
           .map(_.reduceLeftOption(_ |+| _).getOrElse(Model.empty("AST is empty")))
       )
@@ -58,13 +64,15 @@ object Semantics {
     import monocle.macros.syntax.all._
 
     implicit val re: ReportError[F, CompilerState[F]] =
-      (st: CompilerState[F], token: Token[F], hint: String) => st.focus(_.errors).modify(_.append(token -> hint))
+      (st: CompilerState[F], token: Token[F], hint: String) =>
+        st.focus(_.errors).modify(_.append(token -> hint))
 
     implicit val ns: Lens[CompilerState[F], NamesState[F]] = GenLens[CompilerState[F]](_.names)
 
     val names = new NamesInterpreter[F, CompilerState[F]]()
 
-    implicit val as: Lens[CompilerState[F], AbilitiesState[F]] = GenLens[CompilerState[F]](_.abilities)
+    implicit val as: Lens[CompilerState[F], AbilitiesState[F]] =
+      GenLens[CompilerState[F]](_.abilities)
 
     val abilities = new AbilitiesInterpreter[F, CompilerState[F]]()
 
@@ -78,11 +86,13 @@ object Semantics {
     free.foldMap[State[CompilerState[F], *]](interpreter)
   }
 
-  def validate[F[_]](ast: Ast[F]): ValidatedNec[(Token[F], String), Model] =
+  def generateModel[F[_]](ast: Ast[F]): ValidatedNec[(Token[F], String), Model] =
     (transpile[F] _ andThen interpret[F])(ast)
       .run(CompilerState[F]())
       .map { case (state, gen) =>
-        NonEmptyChain.fromChain(state.errors).fold[ValidatedNec[(Token[F], String), Model]](Valid(gen))(Invalid(_))
+        NonEmptyChain
+          .fromChain(state.errors)
+          .fold[ValidatedNec[(Token[F], String), Model]](Valid(gen))(Invalid(_))
       }
       .value
 }
diff --git a/src/main/scala/aqua/semantics/expr/OnSem.scala b/src/main/scala/aqua/semantics/expr/OnSem.scala
index 40236fef..7f246fdf 100644
--- a/src/main/scala/aqua/semantics/expr/OnSem.scala
+++ b/src/main/scala/aqua/semantics/expr/OnSem.scala
@@ -5,6 +5,7 @@ import aqua.parser.expr.OnExpr
 import aqua.semantics.Prog
 import aqua.semantics.rules.ValuesAlgebra
 import aqua.semantics.rules.abilities.AbilitiesAlgebra
+import cats.data.Chain
 import cats.syntax.flatMap._
 import cats.syntax.functor._
 
@@ -24,7 +25,30 @@ class OnSem[F[_]](val expr: OnExpr[F]) extends AnyVal {
       (_: Unit, ops: Model) =>
         A.endScope() as (ops match {
           case op: FuncOp =>
-            FuncOp.wrap(OnTag(ValuesAlgebra.valueToModel(expr.peerId), expr.via.map(ValuesAlgebra.valueToModel)), op)
+            // the way to the node may be lost if there will be chains of `on` without calls
+            // so peerId is added to the path
+            val path = expr.via :+ expr.peerId
+            val returnPath = path.reverse
+            val returnLeaf = {
+              FuncOp.leaf(
+                OnTag(
+                  ValuesAlgebra.valueToModel(returnPath.last),
+                  returnPath.map(ValuesAlgebra.valueToModel)
+                )
+              )
+            }
+
+            FuncOp.node(
+              OnTag(
+                ValuesAlgebra.valueToModel(expr.peerId),
+                path.map(ValuesAlgebra.valueToModel)
+              ),
+              Chain(
+                op,
+                returnLeaf
+              )
+            )
+
           case m => Model.error("On body is not an op, it's " + m)
         })
     )
diff --git a/src/test/scala/aqua/Utils.scala b/src/test/scala/aqua/Utils.scala
index a411caa5..16b7ed27 100644
--- a/src/test/scala/aqua/Utils.scala
+++ b/src/test/scala/aqua/Utils.scala
@@ -1,5 +1,6 @@
 package aqua
 
+import aqua.model.Call
 import aqua.parser.expr.{
   AbilityIdExpr,
   AliasExpr,
@@ -37,17 +38,23 @@ import aqua.semantics.LiteralType.{bool, number, string}
 import aqua.semantics.{LiteralType, ScalarType}
 import org.scalatest.EitherValues
 
+import scala.collection.mutable
 import scala.language.implicitConversions
 
 object Utils {
   implicit def toAb(str: String): Ability[Id] = Ability[Id](str)
 
   implicit def toName(str: String): Name[Id] = Name[Id](str)
+  implicit def toNameOp(str: Option[String]): Option[Name[Id]] = str.map(s => toName(s))
 
-  implicit def toFields(fields: List[String]): List[IntoField[Id]] = fields.map(f => IntoField[Id](f))
+  implicit def toFields(fields: List[String]): List[IntoField[Id]] =
+    fields.map(f => IntoField[Id](f))
 
   implicit def toVar(name: String): VarLambda[Id] = VarLambda[Id](toName(name), Nil)
 
+  implicit def toVarOp(name: Option[String]): Option[VarLambda[Id]] =
+    name.map(s => VarLambda[Id](toName(s), Nil))
+
   implicit def toVarLambda(name: String, fields: List[String]): VarLambda[Id] =
     VarLambda[Id](toName(name), toFields(fields))
   implicit def toLiteral(name: String, t: LiteralType): Literal[Id] = Literal[Id](name, t)
@@ -58,18 +65,30 @@ object Utils {
   implicit def toCustomType(str: String): CustomTypeToken[Id] = CustomTypeToken[Id](str)
   def toArrayType(str: String): ArrayTypeToken[Id] = ArrayTypeToken[Id]((), str)
 
-  implicit def toArrowType(args: List[DataTypeToken[Id]], res: Option[DataTypeToken[Id]]): ArrowTypeToken[Id] =
+  implicit def toArrowType(
+    args: List[DataTypeToken[Id]],
+    res: Option[DataTypeToken[Id]]
+  ): ArrowTypeToken[Id] =
     ArrowTypeToken[Id]((), args, res)
 
-  implicit def toCustomArg(str: String, customType: String): Arg[Id] = Arg[Id](str, toCustomType(customType))
+  implicit def toCustomArg(str: String, customType: String): Arg[Id] =
+    Arg[Id](str, toCustomType(customType))
 
   implicit def toArg(str: String, typeToken: TypeToken[Id]): Arg[Id] = Arg[Id](str, typeToken)
 
+  implicit def toArgSc(str: String, scalarType: ScalarType): Arg[Id] =
+    Arg[Id](str, scToBt(scalarType))
+
   implicit def scToBt(sc: ScalarType): BasicTypeToken[Id] = BasicTypeToken[Id](sc)
+
+  val boolSc: BasicTypeToken[Id] = BasicTypeToken[Id](ScalarType.bool)
+  val stringSc: BasicTypeToken[Id] = BasicTypeToken[Id](ScalarType.string)
 }
 
 trait Utils extends EitherValues {
 
+  val emptyCall = Call(Nil, None)
+
   def parseExpr(str: String): CallArrowExpr[Id] =
     CallArrowExpr.p[Id].parseAll(str).value
 
@@ -110,4 +129,8 @@ trait Utils extends EitherValues {
     ArrowTypeExpr.p[Id].parseAll(str).value
 
   def funcExpr(str: String): FuncExpr[Id] = FuncExpr.p[Id].parseAll(str).value
+
+  implicit class QueueHelper[T](q: mutable.Queue[T]) {
+    def d(): T = q.dequeue()
+  }
 }
diff --git a/src/test/scala/aqua/parser/FuncExprSpec.scala b/src/test/scala/aqua/parser/FuncExprSpec.scala
index 6dd5f840..e51e5bd6 100644
--- a/src/test/scala/aqua/parser/FuncExprSpec.scala
+++ b/src/test/scala/aqua/parser/FuncExprSpec.scala
@@ -1,19 +1,44 @@
 package aqua.parser
 
-import aqua.Utils
-import aqua.parser.Ast.Tree
-import aqua.parser.expr.FuncExpr
-import aqua.parser.lexer.{ArrowTypeToken, BasicTypeToken}
+import aqua.model.{
+  Call,
+  CallArrowTag,
+  CallServiceTag,
+  FuncCallable,
+  LiteralModel,
+  OnTag,
+  OpTag,
+  ScriptModel,
+  SeqTag,
+  XorTag
+}
+import aqua.{SyntaxError, Utils}
+import aqua.parser.Ast.{parser, Tree}
+import aqua.parser.expr.{
+  AbilityIdExpr,
+  ArrowTypeExpr,
+  CallArrowExpr,
+  FuncExpr,
+  IfExpr,
+  OnExpr,
+  ReturnExpr,
+  RootExpr,
+  ServiceExpr
+}
+import aqua.parser.lexer.{ArrowTypeToken, BasicTypeToken, EqOp}
 import aqua.semantics.ScalarType.{bool, u64}
 import cats.{Eval, Id}
 import cats.syntax.traverse._
+import cats.syntax.foldable._
 import org.scalatest.flatspec.AnyFlatSpec
 import org.scalatest.matchers.should.Matchers
 import aqua.parser.lift.LiftParser.Implicits.idLiftParser
+import aqua.semantics.Semantics
 import aqua.semantics.Semantics.{folder, Alg}
-import cats.data.Chain
+import cats.data.{Chain, NonEmptyChain, Validated}
 import cats.free.Cofree
 
+import scala.collection.mutable
 import scala.language.implicitConversions
 
 class FuncExprSpec extends AnyFlatSpec with Matchers with Utils {
@@ -21,18 +46,35 @@ class FuncExprSpec extends AnyFlatSpec with Matchers with Utils {
   import aqua.semantics.ScalarType.{string, u32}
 
   "func header" should "parse" in {
-    funcExpr("func some() -> bool") should be(FuncExpr("some", List(), Some(bool: BasicTypeToken[Id]), None))
+    funcExpr("func some() -> bool") should be(
+      FuncExpr("some", List(), Some(bool: BasicTypeToken[Id]), None)
+    )
     funcExpr("func some()") should be(FuncExpr("some", List(), None, None))
 
-    val arrowToken = ArrowTypeToken[Id]((), List(BasicTypeToken[Id](u32)), Some(BasicTypeToken[Id](bool)))
+    val arrowToken =
+      ArrowTypeToken[Id]((), List(BasicTypeToken[Id](u32)), Some(BasicTypeToken[Id](bool)))
     funcExpr("func some(peer: PeerId, other: u32 -> bool)") should be(
-      FuncExpr(toName("some"), List(toCustomArg("peer", "PeerId"), toArg("other", arrowToken)), None, None)
+      FuncExpr(
+        toName("some"),
+        List(toCustomArg("peer", "PeerId"), toArg("other", arrowToken)),
+        None,
+        None
+      )
     )
 
     val arrowToken2 =
-      ArrowTypeToken[Id]((), List(BasicTypeToken[Id](u32), BasicTypeToken[Id](u64)), Some(BasicTypeToken[Id](bool)))
+      ArrowTypeToken[Id](
+        (),
+        List(BasicTypeToken[Id](u32), BasicTypeToken[Id](u64)),
+        Some(BasicTypeToken[Id](bool))
+      )
     funcExpr("func some(peer: PeerId, other: u32, u64 -> bool)") should be(
-      FuncExpr(toName("some"), List(toCustomArg("peer", "PeerId"), toArg("other", arrowToken2)), None, None)
+      FuncExpr(
+        toName("some"),
+        List(toCustomArg("peer", "PeerId"), toArg("other", arrowToken2)),
+        None,
+        None
+      )
     )
 
     val arrowToken3 = ArrowTypeToken[Id]((), List(BasicTypeToken[Id](u32)), None)
@@ -44,25 +86,26 @@ class FuncExprSpec extends AnyFlatSpec with Matchers with Utils {
         None
       )
     )
-
   }
 
-  "on" should "parse on x: y" in {
-    val script =
-      """func a():
-        | on peer.id:
-        |  x <- Ab.func()
-        |  Peer "some id"
-        |  call(true)""".stripMargin
-
-    val c: Cofree[Chain, Expr[Id]] = FuncExpr.ast[Id](Indent()).parseAll(script).value
-    val a = Ast(c).cata(folder[Id, Alg[Id, *]]).value
-//    a.run
-    println(a)
-
-    FuncExpr.ast[Id](Indent()).parseAll(script).isRight should be(true)
+  def checkHeadGetTail(
+    tree: Cofree[Chain, Expr[Id]],
+    headCheck: Expr[Id],
+    lengthCheck: Int
+  ): Chain[Cofree[Chain, Expr[Id]]] = {
+    tree.head should be(headCheck)
+    val tail = tree.tailForced
+    tail.length should be(lengthCheck)
+    tail
   }
-  "if" should "parse if x == y" in {
+
+  def headTail[T](
+    tree: Cofree[Chain, T]
+  ): (T, List[Cofree[Chain, T]]) = {
+    (tree.head, tree.tailForced.toList)
+  }
+
+  "func expr" should "parse on x: y" in {
     val script =
       """func a():
         | if peer.id == other:
@@ -70,59 +113,153 @@ class FuncExprSpec extends AnyFlatSpec with Matchers with Utils {
         |  Peer "some id"
         |  call(true)""".stripMargin
 
-    FuncExpr.ast[Id](Indent()).parseAll(script).isRight should be(true)
+    val tree = FuncExpr.ast[Id](Indent()).parseAll(script).value
+    val funcBody = checkHeadGetTail(tree, FuncExpr("a", Nil, None, None), 1).toList
+    println("body: " + funcBody)
+
+    val ifBody =
+      checkHeadGetTail(
+        funcBody.head,
+        IfExpr(toVarLambda("peer", List("id")), EqOp[Id](true), toVar("other")),
+        3
+      ).toList
+
+    ifBody.head.head should be(CallArrowExpr(Some(toName("x")), Some(toAb("Ab")), "func", Nil))
+    ifBody(1).head should be(AbilityIdExpr(toAb("Peer"), toStr("some id")))
+    ifBody(2).head should be(CallArrowExpr(None, None, "call", List(toBool(true))))
+
   }
-  /*
 
-    "function" should "parse getTime as a whole" in {
-      val func =
-        """func getTime(peer: PeerId, ret: u32 -> ()) -> string:
-          | on peer:
-          |   Peer "peer"
-          |   t <- Peer.timestamp()
-          | ret(t)""".stripMargin
+  "some" should "other" in {
+    val script =
+      """service Local("local"):
+        |    gt: -> bool
+        |    
+        |func tryGen() -> bool:
+        |    on "deeper" via "deep":
+        |        v <- Local.gt()         
+        |    <- v
+        |
+        |func genC(val: string) -> bool:
+        |    one <- Local.gt() 
+        |    on "smth" via "else":
+        |        two <- tryGen()      
+        |    three <- Local.gt() 
+        |    <- two""".stripMargin
 
-      DefFunc.`deffunc`.parseAll(func).right.value should be(
-        DefFunc[Id, HNil](
-          getTimeHead,
-          NonEmptyList.of(
-            On[Id, HNil](
-              VarLambda[Id]("peer", Nil),
-              NonEmptyList.of(
-                AbilityId[Id, HNil]("Peer", Literal[Id]("\"peer\"", LiteralType.string), HNil),
-                Extract[Id, HNil]("t", AbilityFuncCall[Id, HNil]("Peer", "timestamp", "Peer.timestamp", Nil, HNil), HNil)
-              ),
-              HNil
-            ),
-            FuncCall[Id, HNil]("ret", VarLambda[Id]("t", Nil) :: Nil, HNil)
-          ),
-          HNil
-        )
-      )
+    val tree = parser[Id](Indent()).parseAll(script).value
+
+    val qTree = tree.tree.foldLeft(mutable.Queue.empty[Expr[Id]]) { case (acc, tag) =>
+      acc.enqueue(tag)
     }
 
-    "function" should "parse getTime with no return" in {
-      val func =
-        """func getTime(peer: PeerId, ret: u32 -> ()) -> string:
-          | on peer:
-          |   Peer "peer"
-          |   t <- Peer.timestamp()""".stripMargin
+    qTree.d() shouldBe RootExpr()
+    // Local service
+    qTree.d() shouldBe ServiceExpr(toAb("Local"), Some(toStr("local")))
+    qTree.d() shouldBe ArrowTypeExpr("gt", toArrowType(Nil, Some(scToBt(bool))))
+    qTree.d() shouldBe FuncExpr("tryGen", Nil, Some(scToBt(bool)), Some("v"))
+    qTree.d() shouldBe OnExpr(toStr("deeper"), List(toStr("deep")))
+    qTree.d() shouldBe CallArrowExpr(Some("v"), Some(toAb("Local")), "gt", Nil)
+    qTree.d() shouldBe ReturnExpr(toVar("v"))
+    // genC function
+    qTree.d() shouldBe FuncExpr("genC", List(toArgSc("val", string)), Some(boolSc), Some("two"))
+    qTree.d() shouldBe CallArrowExpr(Some("one"), Some(toAb("Local")), "gt", List())
+    qTree.d() shouldBe OnExpr(toStr("smth"), List(toStr("else")))
+    qTree.d() shouldBe CallArrowExpr(Some("two"), None, "tryGen", List())
+    qTree.d() shouldBe CallArrowExpr(Some("three"), Some(toAb("Local")), "gt", List())
+    qTree.d() shouldBe ReturnExpr(toVar("two"))
 
-      DefFunc.`deffunc`.parseAll(func).right.value should be(
-        DefFunc[Id, HNil](
-          getTimeHead,
-          NonEmptyList.of(
-            On[Id, HNil](
-              VarLambda[Id]("peer", Nil),
-              NonEmptyList.of(
-                AbilityId[Id, HNil]("Peer", Literal[Id]("\"peer\"", LiteralType.string), HNil),
-                Extract[Id, HNil]("t", AbilityFuncCall[Id, HNil]("Peer", "timestamp", "Peer.timestamp", Nil, HNil), HNil)
-              ),
-              HNil
-            )
-          ),
-          HNil
-        )
-      )
-    }*/
+    val f =
+      Semantics.generateModel(tree).toList.head.asInstanceOf[ScriptModel]
+
+    val funcs = f.funcs.toList
+    val funcTryGen = funcs.head
+    val funcOpTryGen = funcTryGen.body.resolveTopology()
+
+    val qTryGen = funcOpTryGen.tree.foldLeft(mutable.Queue.empty[OpTag]) { case (acc, tag) =>
+      acc.enqueue(tag)
+    }
+
+    val smth = LiteralModel("\"smth\"")
+    val smthOn = OnTag(smth, Nil)
+    val smthCall = CallServiceTag(
+      LiteralModel("\"op\""),
+      "identity",
+      emptyCall,
+      Some(LiteralModel("\"smth\""))
+    )
+
+    val elseL = LiteralModel("\"else\"")
+    val elseOn = OnTag(elseL, Nil)
+    val elseCall = CallServiceTag(
+      LiteralModel("\"op\""),
+      "identity",
+      emptyCall,
+      Some(LiteralModel("\"else\""))
+    )
+
+    val deeper = LiteralModel("\"deeper\"")
+    val deeperOn = OnTag(deeper, Nil)
+    val deeperCall = CallServiceTag(
+      LiteralModel("\"op\""),
+      "identity",
+      emptyCall,
+      Some(LiteralModel("\"deeper\""))
+    )
+    val deep = LiteralModel("\"deep\"")
+    val deepOn = OnTag(deep, Nil)
+    val deepCall = CallServiceTag(
+      LiteralModel("\"op\""),
+      "identity",
+      emptyCall,
+      Some(LiteralModel("\"deep\""))
+    )
+    val local = LiteralModel("\"local\"")
+
+    // tag that we will go to 'deeper'
+    qTryGen.d() shouldBe deeperOn
+    // move to 'deep' node
+    qTryGen.d() shouldBe deepOn
+    qTryGen.d() shouldBe deepCall
+    // move to 'deeper' node
+    qTryGen.d() shouldBe deeperOn
+    qTryGen.d() shouldBe deeperCall
+    // a call must be with `on` too, so we need to call 'deeper' after we will go out of the scope
+    qTryGen.d() shouldBe CallServiceTag(local, "gt", Call(Nil, Some("v")), Some(deeper))
+    qTryGen.d() shouldBe deepOn
+    // return to 'deeper' node
+    qTryGen.d() shouldBe deeperOn
+    qTryGen.d() shouldBe deeperCall
+    // return to 'deep' node
+    qTryGen.d() shouldBe deepOn
+    qTryGen.d() shouldBe deepCall
+
+    val funcGenComplex = f.funcs.toList(1)
+    val funcOpGenComplex = funcGenComplex.body.resolveTopology()
+
+    val qGenComplex = funcOpGenComplex.tree.foldLeft(mutable.Queue.empty[OpTag]) {
+      case (acc, tag) =>
+        acc.enqueue(tag)
+    }
+
+    qGenComplex.d() shouldBe SeqTag
+    qGenComplex.d() shouldBe CallServiceTag(local, "gt", Call(List(), Some("one")), None)
+    // tag that we will go to 'smth'
+    qGenComplex.d() shouldBe smthOn
+    // move to 'else' node
+    qGenComplex.d() shouldBe elseOn
+    qGenComplex.d() shouldBe elseCall
+    // move to 'smth' node
+    qGenComplex.d() shouldBe smthOn
+    qGenComplex.d() shouldBe smthCall
+    qGenComplex.d() shouldBe CallArrowTag(None, "tryGen", Call(List(), Some("two")))
+    qGenComplex.d() shouldBe elseOn
+    // return to 'smth' node
+    qGenComplex.d() shouldBe smthOn
+    qGenComplex.d() shouldBe smthCall
+    // return to 'else' node
+    qGenComplex.d() shouldBe elseOn
+    qGenComplex.d() shouldBe elseCall
+    qGenComplex.d() shouldBe CallServiceTag(local, "gt", Call(List(), Some("three")), None)
+  }
 }