Adds MODULE HELP and implements addReplySubSyntaxError

src/networking.c

@@ -560,6 +560,18 @@ void addReplyHelp(client *c, const char **help) {
     setDeferredMultiBulkLength(c,blenp,blen);
 }
 
+/* Add a suggestive error reply.
+ * This function is typically invoked by from commands that support
+ * subcommands in response to an unknown subcommand or argument error. */
+void addReplySubSyntaxError(client *c) {
+    sds cmd = sdsnew((char*) c->argv[0]->ptr);
+    sdstoupper(cmd);
+    addReplyErrorFormat(c,
+        "Unknown subcommand or wrong number of arguments for '%s'. Try %s HELP.",
+        c->argv[1]->ptr,cmd);
+    sdsfree(cmd);    
+}
+
 /* Copy 'src' client output buffers into 'dst' client output buffers.
  * The function takes care of freeing the old output buffers of the
  * destination client. */