Handling keyword arguments default values

kw.py

# python 2
def foo(**kwargs):
    x = kwargs.pop('x', 10)
    y = kwargs.pop('y', 'no value')
    if kwargs:
        raise TypeError('unknown keyword arguments: %s' % kwargs.keys())
    print x, y
        
        
# python 3
 def foo(*, x=10, y='no value'):
    print(x, y)

def foo(bar, hello='world'):
    pass

def test_foo_kwargs():
    foo(True)
    assert foo.kwargs == {'hello': 'world'}