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

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


    >>> import hashlib
    >>> import gzip
    >>> import re2
    >>> re2.set_fallback_notification(re2.FALLBACK_EXCEPTION)
    >>> with gzip.open('wikipages.xml.gz', 'rb') as tmp:
    ...     data = tmp.read()
    >>> print(hashlib.md5(re2.sub(b'\(.*?\)', b'', data)).hexdigest())
    b7a469f55ab76cd5887c81dbb0cfe6d3
