Function objects are mutable, so I expected that a copy of a function should be an actual independent copy. But it isn't.

    py> from copy import copy
    py> a = lambda: 1
    py> b = copy(a)
    py> a is b
    True

This burned me when I modified the copy and the original changed too:

    py> a.attr = 27  # add extra data
    py> b.attr = 42
    py> a.attr
    42


`deepcopy` doesn't copy the function either.