p>
<p>This mixin has a basic implementation of all but five of the members of
<a href="dart-core/Map-class.html">Map</a>.
A basic <code>Map</code> class can be implemented by mixin in this class and
implementing <code>keys</code>, <code>operator[]</code>, <code>operator[]=</code>, <code>remove</code> and <code>clear</code>.
The remaining operations are implemented in terms of these five.</p>
<p>The <code>keys</code> iterable should have efficient <a href="dart-collection/MapMixin/length.html">Iterable.lengt