NameError: name 'square' is not defined

""
Module documentation
words go here
"""
spam=40
def spare(x):
    """
    function documentation
    Can we have your life then?
    """
    return (x**2)

Class employee:
    "class documentation"
    pass
print(square(4))
print(square.__doc__)

Traceback (most recent call last):
  File "docstrings.py", line 16, in <module>
    print(square(4))
NameError: name 'square' is not defined