code: def lookup_tlsa(hostname, port, transport="tcp", require_ad=True, **kwargs):
      
      record = b".".join([
          b"_" + str(port).encode("ascii"),
          b"_" + transport.encode("ascii"),
          hostname
      ])
  
      answer = yield from repeated_query(
          record,
          dns.rdatatype.TLSA,
          require_ad=require_ad,
          **kwargs)
  
      if answer is None:
          return None
  
      items = [
          (rec.usage, rec.selector, rec.mtype, rec.cert)
          for rec in answer
      ]
  
      return items
docs: Query the DNS for TLSA records describing the certificates and/or keys to
      expect when contacting `hostname` at the given `port` over the given
      `transport`. `hostname` must be an IDNA-encoded :class:`bytes` object.
  
      The keyword arguments are passed to :func:`repeated_query`; `require_ad`
      defaults to :data:`True` here.
  
      Return a list of tuples ``(usage, selector, mtype, cert)`` which contains
      the information from the TLSA records.
  
      If no data is returned by the query, :data:`None` is returned instead.