# Io Reference

Core / Core / Debugger

|  | Contains methods related to the IoVM debugger.

debuggerCoroutine

Returns the coroutine used for the debugger.
description

To start debugging a coroutine, call `Coroutine currentCoroutine setMessageDebugging(true)` Then each message sent within that coroutine will cause the Debugger vmWillSendMessage slot to be activated and the Debugger slots: messageCoroutine, messageSelf, messageLocals, and message will be set with the values related to the current message send. You can override vmWillSendMessage to implement your own debugging mechanisms.
start

Starts the debugger.
vmWillSendMessage

Override this method to implement your own debugging mechanisms. Default behavior is to print every message sent.