This variable holds current state of the assigned time line and
will return true if it is running and false if it is not.
You can also set this variable to either true or
false to start and stop the time line at any time. it
should be noted that a stopped time line is not reset, and
so starting it again at a later time will start it from the exact
moment that it was stopped at.
timeline_position = 0;
timeline_running = true;
The above code will check to see if the instance is running a time line, and if it is not then it resets the assigned time line to start at the first moment and then starts it.