Added bin() builtin.  I'm going to check in the tests in a seperate checkin, because the builtin doesn't need to be ported to py3k, but the tests are missing in py3k and need to be merged there.
Added bin() builtin.  I'm going to check in the tests in a seperate checkin, because the builtin doesn't need to be ported to py3k, but the tests are missing in py3k and need to be merged there.

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