def renumber(map)
      raise "player number #{@num} not found in renumbering hash" unless map[@num]
      self.num = map[@num]
      @results.each{ |r| r.renumber(map) }
      self
    end
def renumber(map)
      raise "player number #{@num} not found in renumbering hash" unless map[@num]
      self.num = map[@num]
      @results.each{ |r| r.renumber(map) }
      self
    end
Renumber the player according to the supplied hash. Return self.