def reverse
      return unless @opponent
      r = Result.new(@round, @opponent, @score == 'W' ? 'L' : (@score == 'L' ? 'W' : 'D'))
      r.opponent = @player
      r.colour = 'W' if @colour == 'B'
      r.colour = 'B' if @colour == 'W'
      r.rateable = @rateable
      r
    end
def reverse
      return unless @opponent
      r = Result.new(@round, @opponent, @score == 'W' ? 'L' : (@score == 'L' ? 'W' : 'D'))
      r.opponent = @player
      r.colour = 'W' if @colour == 'B'
      r.colour = 'B' if @colour == 'W'
      r.rateable = @rateable
      r
    end
Return a reversed version (from the opponent's perspective) of a result.