# File lib/facets/core/string/at_rand.rb, line 25
  def at_rand!( separator=// )
    separator = self.class.patterns( separator )
    a = self.shatter( separator )
    w = []; a.each_with_index { |s,i| i % 2 == 0 ? w << s : w.last << s }
    i = rand( w.size )
    r = w.delete_at( i )
    self.replace( w.join('') )
    return r
  end