# File lib/tracelines19.rb, line 8
  def self.lnums_for_str src
    name = "#{Time.new.to_i}_#{rand(2**31)}"
    iseq = RubyVM::InstructionSequence.compile(src, name)
    lines = {}
    iseq.disasm.each_line{|line|
      if /^\d+ (\w+)\s+.+\(\s*(\d+)\)$/ =~ line
        insn = $1
        lineno = $2.to_i
        next unless insn == 'trace'
        lines[lineno] = true
        # p [lineno, line]
      end
    }
    lines.keys
  end