Add values.

doc/API.md

@@ -25,6 +25,7 @@
     - [slice(start[, end]) -> Channel](#slicestart-end---channel)
     - [some(callbackfn[, thisArg])](#somecallbackfn-thisarg)
     - [toString()](#tostring)
+    - [values() -> async iterator](#values---async-iterator)
 - [Functional API](#functional-api)
 
 <!-- /TOC -->
@@ -310,6 +311,10 @@ empty channel, it returns `false`.
 
 Return `"Channel(n)"` where `n` is the length of the buffer.
 
+### values() -> async iterator
+
+Return an iterator over the values in the channel.
+
 # Functional API
 
 There is a parallel API to support functional-style programming.  Every channel