code: def decode(tai64n):
      
      seconds, nanoseconds = struct.unpack(_STRUCTURE, a2b_hex(tai64n[1:]))
      seconds -= _OFFSET
      return seconds + (nanoseconds / 1000000000.0)
docs: Convert TAI64N string to seconds since epoch.
  
      Note that dates before 2013 may not decode accurately due to leap second
      issues. If you need correct decoding for earlier dates you can try the
      tai64n package available from PyPI (U{https://pypi.python.org/pypi/tai64n}).
  
      @param tai64n: TAI64N-encoded time, as C{unicode}.
  
      @return: Seconds since UTC Unix epoch as C{float}.