>>> from sys import mod
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
ImportError: cannot import name mod

def foo(): pass
bar = foo

>>> import demo
>>> from demo import *
>>> demo.foo is foo
True
>>> id(demo.foo) == id(foo)
True
>>> demo.bar is foo
True

# define modulus f
def mod(a,b):
    return b % a

print mod(5,2)

modulus=mod
print modulus(5,2)

myat=math.atanh

myat(x)