Tests of substitution
=====================

This first test is just looking to replace things between parentheses
with an empty string.


    >>> import re2 as re
    >>> import hashlib
    >>> import gzip
    >>> data = gzip.open('wikipages.xml.gz').read()
    >>> print hashlib.md5(re.sub('\(.*?\)', '', data)).hexdigest()
    b7a469f55ab76cd5887c81dbb0cfe6d3
