# File lib/facet/string/first&last.rb, line 31
  def last(n=1, separator=$/)
    separator = /\n+/ if separator == ''
    separator = /\s+/ unless separator
    separator = Regexp.new( Regexp.escape( separator ) ) if String === separator
    rself = self.reverse
    i,s = 0,0
    n.times { i = rself.index(separator,s); s = $~.end(0) }
    return rself[0...i].reverse
  end