Document the `dispatch()` attribute

pep-0443.txt

@@ -97,8 +97,8 @@ To enable registering lambdas and pre-existing functions, the
   >>> fun.register(type(None), nothing)
 
 The ``register()`` attribute returns the undecorated function which
-enables decorator stacking, as well as creating unit tests for each
-variant independently::
+enables decorator stacking, pickling, as well as creating unit tests for
+each variant independently::
 
   >>> @fun.register(float)
   ... @fun.register(Decimal)
@@ -126,9 +126,17 @@ When called, the generic function dispatches on the first argument::
   3 spam
   >>> fun(None)
   Nothing.
-  >>> fun_num(1.23)
+  >>> fun(1.23)
   0.615
 
+To get the implementation for a specific type, use the ``dispatch()``
+attribute::
+
+  >>> fun.dispatch(float)
+  <function fun_num at 0x104319058>
+  >>> fun.dispatch(dict)
+  <function fun at 0x103fe4788>
+
 The proposed API is intentionally limited and opinionated, as to ensure
 it is easy to explain and use, as well as to maintain consistency with
 existing members in the ``functools`` module.