'Returns a boto.s3.key.Key object matching the regular expression
:param regex_key: the path to the key
:type regex_key: str
:param bucket_name: the name of the bucket
:type bucket_name: str'

def get_wildcard_key(self, wildcard_key, bucket_name=None, delimiter=''):

    if (not bucket_name):
        (bucket_name, wildcard_key) = self.parse_s3_url(wildcard_key)
    bucket = self.get_bucket(bucket_name)
    prefix = re.split('[*]', wildcard_key, 1)[0]
    klist = self.list_keys(bucket_name, prefix=prefix, delimiter=delimiter)
    if (not klist):
        return None
    key_matches = [k for k in klist if fnmatch.fnmatch(k, wildcard_key)]
    return (bucket.get_key(key_matches[0]) if key_matches else None)
