CoCalc provides the best real-time collaborative environment for Jupyter Notebooks, LaTeX documents, and SageMath, scalable from individual users to large groups and classes!

1
class String
2
  @@idx_reported = {}
3
  def [](*args)
4
    if args.length == 1 && args[0].class == ::Integer && !@@idx_reported[caller[0].to_s]
5
      $stderr.puts "HOOK: String[idx] #{caller.join("\t")}\n\n"
6
      @@idx_reported[caller[0].to_s] = true
7
    end
8
    slice(*args)
9
  end
10
end
11

12