How can I dynamically get the set of classes from the current python module?

class A(object):
    def __call__(self):
        print "ran a"

class B(object):
    def __call__(self):
        print "ran b"

class C(object):
    def __call__(self):
        print "ran c"

import sys
getattr(sys.modules[__name__], 'A')

import sys
import types
this_module = sys.modules[__name__]
[x for x in
    [getattr(this_module, x) for x in dir(this_module)]
    if type(x) == types.ClassType]