Add ImportObject maybe_with_namespace example

CHANGELOG.md

@@ -6,6 +6,7 @@ Blocks of changes will separated by version increments.
 
 ## **[Unreleased]**
 
+- [#833](https://github.com/wasmerio/wasmer/pull/833) Add doc example of using ImportObject's new `maybe_with_namespace` method
 - [#832](https://github.com/wasmerio/wasmer/pull/832) Delete unused runtime ABI
 - [#809](https://github.com/wasmerio/wasmer/pull/809) Fix bugs leading to panics in `LocalBacking`.
 - [#822](https://github.com/wasmerio/wasmer/pull/822) Update Cranelift fork version to `0.43.1`

lib/runtime-core/src/import.rs

@@ -124,6 +124,14 @@ impl ImportObject {
     }
 
     /// The same as `with_namespace` but takes a function that may fail
+    /// # Usage:
+    /// ```
+    /// # use wasmer_runtime_core::import::{ImportObject, LikeNamespace};
+    /// # use wasmer_runtime_core::export::Export;
+    /// fn get_export(imports: &ImportObject, namespace: &str, name: &str) -> Option<Export> {
+    ///     imports.maybe_with_namespace(namespace, |ns| ns.get_export(name))
+    /// }
+    /// ```
     pub fn maybe_with_namespace<Func, InnerRet>(&self, namespace: &str, f: Func) -> Option<InnerRet>
     where
         Func: FnOnce(&(dyn LikeNamespace + Send)) -> Option<InnerRet>,