code: func NewExpander(r io.Reader, dict []byte) *Expander {
  	e := Expander{}
  	e.r = r
  	e.to = 0
  	e.dict = dict
  	return &e
  }
docs: // NewExpander creates a new decompressor.  Pass in an io.Reader that
  // can be used to read the raw compressed data.  The Expander
  // implements io.Reader and so calling Read() decompress data and
  // reads the actual input.