How to use the pycares.QUERY_TYPE_MX function in pycares

def test_query_mx(self):
        self.result, self.errorno = None, None
        def cb(result, errorno):
            self.result, self.errorno = result, errorno
        self.channel.query('google.com', pycares.QUERY_TYPE_MX, cb)
        self.wait()
        self.assertNoError(self.errorno)
        for r in self.result:
            self.assertEqual(type(r), pycares.ares_query_mx_result)
            self.assertTrue(r.ttl >= 0)

from . import error


__version__ = '2.0.0'

__all__ = ('DNSResolver', 'error')


READ = 1
WRITE = 2

query_type_map = {'A'     : pycares.QUERY_TYPE_A,
                  'AAAA'  : pycares.QUERY_TYPE_AAAA,
                  'ANY'   : pycares.QUERY_TYPE_ANY,
                  'CNAME' : pycares.QUERY_TYPE_CNAME,
                  'MX'    : pycares.QUERY_TYPE_MX,
                  'NAPTR' : pycares.QUERY_TYPE_NAPTR,
                  'NS'    : pycares.QUERY_TYPE_NS,
                  'PTR'   : pycares.QUERY_TYPE_PTR,
                  'SOA'   : pycares.QUERY_TYPE_SOA,
                  'SRV'   : pycares.QUERY_TYPE_SRV,
                  'TXT'   : pycares.QUERY_TYPE_TXT
        }


class DNSResolver:
    def __init__(self, nameservers: Optional[List[str]] = None, loop: Optional[asyncio.AbstractEventLoop] = None,
                 **kwargs: Any) -> None:
        self.loop = loop or asyncio.get_event_loop()
        assert self.loop is not None
        kwargs.pop('sock_state_cb', None)
        self._channel = pycares.Channel(sock_state_cb=self._sock_state_cb, **kwargs)