Mad_libs.py

import re

text = """ Giraffes have aroused
the curiosity of __PLURAL_NOUN__ 
since earliest times. The 
giraffe is the tallest of all 
living __PLURAL_NOUN__, but 
scientists are unable to 
explain how it got its long 
__PART_OF_THE_BODY__. The 
giraffe's tremendous height, 
which might reach __NUMBER__ 
__PLURAL_NOUN__, comes from 
it legs and __BODYPART__.
"""

def mad_libs(mls):
    """
    :param mls: String
    with parts the user
    should fill out surrounded
    by double underscores.
    Underscores cannot
    be inside hint e.g., no
    __hint_hint__ only
    __hint__.
    """
    hints = re.findall("__.*?__", mls)

    if hints is not None:
        for word in hints:
            q = "Enter a {}"\
                .format(word)
            new = input(q)
            mls = mls.replace(word, new, 1)
            print('\n')
            mls = mls.replace("\n", "")
        print(mls)
    else:
        print("invalid mls")

mad_libs(text)