#!/usr/bin/env python 
"""Function with one argument."""
def DoubleIt(x):
    """Function doc comes first, if the name (which
    is a verb according to the style guide) isn't
    sufficient documentation.
    """
    return 2 * x

print (DoubleIt(2))
print (DoubleIt("Hi"))
print (DoubleIt(2.2))
"""
$ double.py
4
HiHi
4.4
$
"""