# File lib/trollop.rb, line 429
  def die(arg, msg = nil, error_code = nil)
    msg, error_code = nil, msg if msg.kind_of?(Integer)
    if msg
      $stderr.puts "Error: argument --#{@specs[arg].long} #{msg}."
    else
      $stderr.puts "Error: #{arg}."
    end
    if @educate_on_error
      $stderr.puts
      educate $stderr
    else
      $stderr.puts "Try --help for help."
    end
    exit(error_code || -1)
  end