Takes an identifier (like a username or IP address) and converts it
            into a key usable by the cache system.

def convert_identifier_to_key(identifier):
        """ Takes an identifier (like a username or IP address) and converts it
            into a key usable by the cache system.
        """
        key = ''.join(c for c in identifier if c.isalnum() or c in '_.-')
        if len(key) > 230:
            key = key[:150] + '-' + hashlib.md5(key).hexdigest()

        return "%s_accesses" % key