prelude: |
  # get last backtrace
benchmark:
  vm3_backtrace: |

    begin
      caller(0, 0)
    rescue ArgumentError
      alias caller_orig caller
      def caller lev, n
        caller_orig(lev)[0..n]
      end
    end

    def rec n
      if n < 0
        100_000.times{
          caller(0, 1)
        }
      else
        rec(n-1)
      end
    end

    rec 50
loop_count: 1