def cacheResult(self, query, payload, cacheTime=None):
        """
        Cache a DNS entry.

        @param query: a L{dns.Query} instance.

        @param payload: a 3-tuple of lists of L{dns.RRHeader} records, the
            matching result of the query (answers, authority and additional).

        @param cacheTime: The time (seconds since epoch) at which the entry is
            considered to have been added to the cache. If L{None} is given,
            the current time is used.
        """
        if self.verbose > 1:
            log.msg('Adding %r to cache' % query)

        self.cache[query] = (cacheTime or self._reactor.seconds(), payload)

        if query in self.cancel:
            self.cancel[query].cancel()

        s = list(payload[0]) + list(payload[1]) + list(payload[2])
        if s:
            m = s[0].ttl
            for r in s:
                m = min(m, r.ttl)
        else:
            m = 0

        self.cancel[query] = self._reactor.callLater(m, self.clearEntry, query)

        Cache a DNS entry.

        @param query: a L{dns.Query} instance.

        @param payload: a 3-tuple of lists of L{dns.RRHeader} records, the
            matching result of the query (answers, authority and additional).

        @param cacheTime: The time (seconds since epoch) at which the entry is
            considered to have been added to the cache. If L{None} is given,
            the current time is used.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/names/cache.py