"""
 advent9.py

 advent of code day 9
"""

import re

def dump_exclamation(stream):
    """ Remove !. from stream. Return new version 
        >>> dump_exclamation('!!abc!abbb')
        'abcbbb'
    """
    return re.sub(r'!.', '', stream)

# test regular expression in python :
# print re.sub(r'^(.*)(ab)(cd)(.*)$', 
#             r'\1\3\2\4', "__abcde__")

def main():
    data = open("day9_input.txt").read()

if __name__ == "__main__":
    import doctest
    doctest.testmod()
    main()