Minor cleanups: * Avoid creating unused local variables where we can.  Where we can't prefix   the unused variables with '_'. * Avoid shadowing builtins where it won't change the external interface of a   function. * Use None as default path arg to readmodule and readmodule_ex.
Minor cleanups:
* Avoid creating unused local variables where we can.  Where we can't prefix
  the unused variables with '_'.
* Avoid shadowing builtins where it won't change the external interface of a
  function.
* Use None as default path arg to readmodule and readmodule_ex.

sk-/python2.7-type-annotator,sk-/python2.7-type-annotator,sk-/python2.7-type-annotator