(This is Part 4 of our ongoing series about Dart. Check out Part 3: Lists and arrays in Dart .)Warning: We expect the Dart libraries to undergo potentially sweeping changes before Dart goes to alpha. This document is relevant as of 2012-01-02.IntroDart is not just a language, but a full "batteries included" effort to create a productive, familiar, and fun environment for the modern web app developer. The bundled libraries are one such "battery", including many common classes and utilities such as date manipulation, regular expressions, even asynchronous constructs like Future and Promise.Probably the most used set of libraries will be the Collections, such as List, Map, and Set. In this post, we'll take a look at Map , which is a mapping of keys to values.In Dart, a Map is an interface designed to manipulate a collection of keys which point to values. Maps can have null values, and can have parameterized types. Note, Maps do not subclass the Collection interfa…