import types

xyz = 123

def abc():
    return xyz
assert abc() == 123

# fails
new_abc = types.FunctionType(
    abc.func_code,
    {'xyz': 456},
    abc.func_name,
    abc.func_defaults,
    abc.func_closure)
assert new_abc() == 456

# this too
sm = type(globals())()
sm.update({'xyz': 456})
sm_abc = types.FunctionType(
    abc.func_code,
    sm,
    abc.func_name,
    abc.func_defaults,
    abc.func_closure)
assert sm_abc() == 456