I see, thank you!
Let me just explain my intentions. I am working on a tool - Controller, that will help creative developers to test their work with animation. I am developing a class, to which people can pass their timeline, but what if developer uses multiple timelines in one creative? In this case I added globalTimeline. So just to sum up, if a developer has 1 timeline, this timeline is passed to a class, but if there are multiple ones, there is no need to pass any, because the default timeline is globalTimeline.
Could you please suggest how to work with such kind of situations?