class Optimizing

  def assert(cond)
    if !cond
      raise "Assert Failure"
    end
  end

  def color_by_score(score)
    assert (score >= 0 && score <= 100)

    case
    when score >= 80 && score <= 100
      "green"
    when score >= 60
      "yellow"
    when score >= 0
      "red"
    end
  end
end

o = Optimizing.new

(0..100).to_a.each do |i|
  puts "#{i}: #{o.color_by_score(i)}"
end

begin
  o.color_by_score 101
rescue e: Exception
  puts "Exception: #{e}"
end