execute (Debugger::IRBCommand)

    # File cli/ruby-debug/commands/irb.rb, line 51
        def execute
          unless @state.interface.kind_of?(LocalInterface)
            print "Command is available only in local mode.\n"
            throw :debug_error
          end

          save_trap = trap("SIGINT") do
            throw :IRB_EXIT, :cont if $debug_in_irb
          end

          $debug_in_irb = true
          cont = IRB.start_session(get_binding)
          if cont == :cont
            @state.proceed
          else
            file = @state.context.frame_file(0)
            line = @state.context.frame_line(0)
            CommandProcessor.print_location_and_text(file, line)
            @state.previous_line = nil
          end

        ensure
          $debug_in_irb = false
          trap("SIGINT", save_trap) if save_trap
        end