def matches_regexp(pattern):
    """Matches if object is a string containing a match for a given regular
    expression.

    :param pattern: The regular expression to search for.

    This matcher first checks whether the evaluated object is a string. If so,
    it checks if the regular expression ``pattern`` matches anywhere within the
    evaluated object.

    """
    if isinstance(pattern, six.string_types):
        pattern = re.compile(pattern)

    return StringMatchesPattern(pattern)
Matches if object is a string containing a match for a given regular
    expression.

    :param pattern: The regular expression to search for.

    This matcher first checks whether the evaluated object is a string. If so,
    it checks if the regular expression ``pattern`` matches anywhere within the
    evaluated object.

    
stackoverflow/venv/lib/python3.6/site-packages/hamcrest/library/text/stringmatches.py