code: def encode(timestamp):
      
      seconds = int(timestamp)
      nanoseconds = int((timestamp - seconds) * 1000000000)
      seconds = seconds + _OFFSET
      encoded = b2a_hex(struct.pack(_STRUCTURE, seconds, nanoseconds))
      return "@" + encoded.decode("ascii")
docs: Convert seconds since epoch to TAI64N string.
  
      @param timestamp: Seconds since UTC Unix epoch as C{float}.
  
      @return: TAI64N-encoded time, as C{unicode}.