# File lib/facet/string/first&last.rb, line 13
  def first(n=1, separator=$/)
    separator = /\n+/ if separator == ''
    separator = /\s+/ unless separator
    separator = Regexp.new( Regexp.escape( separator ) ) if String === separator
    i,s = 0,0
    n.times { i = self.index(separator,s); s = $~.end(0) }
    return self[0...i]
  end