code: func (t *FST) pack(minInCountDeref, maxDerefNodes int,
  	acceptableOverheadRatio float32) (*FST, error) {
  	panic("not implemented yet")
  }
docs: // L1464
  /*
  Expert: creates an FST by packing this one. This process requires
  substantial additional RAM (currently up to ~8 bytes per node
  depending on acceptableOverheadRatio), but then should produce a
  smaller FST.
  
  The implementation of this method uses ideas from
  <a target="_blank" href="http://www.cs.put.poznan.pl/dweiss/site/publications/download/fsacomp.pdf">Smaller Representation of Finite State Automata</a>
  which describes techniques to reduce the size of a FST. However, this
  is not a strict implementation of the algorithms described in this
  paper.
  */