How to use the pycares.errno.strerror function in pycares

def test_strerror_str(self):
        for key in pycares.errno.errorcode:
            self.assertTrue(type(pycares.errno.strerror(key)), str)

def resolve(self, host, port, family=0):
        if is_valid_ip(host):
            addresses = [host]
        else:
            # gethostbyname doesn't take callback as a kwarg
            self.channel.gethostbyname(host, family, (yield gen.Callback(1)))
            callback_args = yield gen.Wait(1)
            assert isinstance(callback_args, gen.Arguments)
            assert not callback_args.kwargs
            result, error = callback_args.args
            if error:
                raise Exception('C-Ares returned error %s: %s while resolving %s' %
                                (error, pycares.errno.strerror(error), host))
            addresses = result.addresses
        addrinfo = []
        for address in addresses:
            if '.' in address:
                address_family = socket.AF_INET
            elif ':' in address:
                address_family = socket.AF_INET6
            else:
                address_family = socket.AF_UNSPEC
            if family != socket.AF_UNSPEC and family != address_family:
                raise Exception('Requested socket family %d but got %d' %
                                (family, address_family))
            addrinfo.append((address_family, (address, port)))
        raise gen.Return(addrinfo)

def _ares_cb(self, cb, result, error):
        if error is not None:
            error_data = self._ares_errno_map.get(error)
            if not error_data:
                exc = socket.gaierror(error, pycares.errno.strerror(error))
            else:
                klass, args = error_data
                exc = klass(*args)
            cb(Result(None, exc))
        else:
            cb(Result(result, None))

def cb(result, error):
    if error is not None:
        print('Error: (%d) %s' % (error, pycares.errno.strerror(error)))
    else:
        parts = [
            ';; QUESTION SECTION:',
            ';%s\t\t\tIN\t%s' % (hostname, qtype.upper()),
            '',
            ';; ANSWER SECTION:'
        ]

        if not isinstance(result, collections.abc.Iterable):
            result = [result]

        for r in result:
            txt = '%s\t\t%d\tIN\t%s' % (hostname, r.ttl, r.type)
            if r.type in ('A', 'AAAA'):
                parts.append('%s\t%s' % (txt, r.host))
            elif r.type == 'CNAME':

def _getnameinfo(self, future, sockaddr, result, error):
        if error:
            future.set_exception(
                Exception('C-Ares returned error %s: %s while resolving %s' %
                          (error, pycares.errno.strerror(error),
                           str(sockaddr))))
        else:
            service = result.service
            if not service:
                service = 'https' if sockaddr[1] == 443 else 'http'
            future.set_result((result.node, service))