docs: def h2i(self, pkt, seconds):
          """Convert the number of seconds since 1-Jan-70 UTC to the packed
             representation."""
  
          if seconds is None:
              seconds = 0
  
          tmp_short = (seconds >> 32) & 0xFFFF
          tmp_int = seconds & 0xFFFFFFFF
  
          return struct.pack("!HI", tmp_short, tmp_int)