Clarify the transition plan for the 2to3 fixer. Also link directly to the

fixer itself.

pep-3113.txt

@@ -216,13 +216,12 @@ emitted when Python's compiler comes across a tuple parameter in
 Python 2.6.  This will be treated like any other syntactic change that
 is to occur in Python 3.0 compared to Python 2.6.
 
-Second, the 2to3 refactoring tool [#2to3]_ will gain a rule for
-translating tuple parameters to being a single parameter that is
-unpacked as the first statement in the function.  The name of the new
-parameter will be a mangling of tuple parameter's names by joining
-them with underscores.  The new parameter will then be unpacked into
-the names originally used in the tuple parameter.  This means that the
-following function::
+Second, the 2to3 refactoring tool [#2to3]_ will gain a fixer
+[#fixer]_ for translating tuple parameters to being a single parameter
+that is unpacked as the first statement in the function.  The name of
+the new parameter will be changed.  The new parameter will then be
+unpacked into the names originally used in the tuple parameter.  This
+means that the following function::
 
  def fxn((a, (b, c))):
      pass
@@ -233,6 +232,17 @@ will be translated into::
      (a, (b, c)) = a_b_c
      pass
 
+As tuple parameters are used by lambdas because of the single
+expression limitation, they must also be supported.  This is done by
+having the expected sequence argument bound to a single parameter and
+then indexing on that parameter::
+
+ lambda (x, y): x + y
+
+will be translated into::
+
+ lambda x_y: x_y[0] + x_y[1]
+
 
 References
 ==========
@@ -240,6 +250,9 @@ References
 .. [#2to3] 2to3 refactoring tool
     (http://svn.python.org/view/sandbox/trunk/2to3/)
 
+.. [#fixer] 2to3 fixer
+    (http://svn.python.org/view/sandbox/trunk/2to3/fixes/fix_tuple_params.py)
+
 .. [#ironpython] IronPython
     (http://www.codeplex.com/Wiki/View.aspx?ProjectName=IronPython)