Red-Black Trees: Apply

We might want to apply some function to all the values in the map:

    linux$ my

    eval:  include string_map;

    eval:  m = empty: Map( String );

    eval:  m $= ("Key1", "Value1");
    eval:  m $= ("Key2", "Value2");
    eval:  m $= ("Key3", "Value3");

    eval:  apply (printf "<<%s>>\n") m;
    <<Value1>>
    <<Value2>>
    <<Value3>>

    ()