dunder_test.py

class A(object):
    def method(self):
        print "I'm method in A"

    def __method__(self):
        print "I'm __method__ in A"
    
    def __method(self):
        print "I'm __method in A"

a = A()
print hasattr(a, 'method')          # True
print hasattr(a, '__method__')      # True
print hasattr(a, '__method')        # False
print hasattr(a, '_A__method')      # True