pehrlich

def expression_backtrace(backtrace)
  new_trace = []
  backtrace.each do |line|
    match = /(.*):([0-9]+):in/.match line
    file, linenum = match[1], match[2].to_i

    new_trace << line

    if File.exist?(file)
      expr = File.readlines(file)[linenum - 1]