matplotlib/matplotlib — pull request #1887 by alito (2013-04-07 13:08:50+00:00)
Title: Clarify documentation for FuncAnimation

The current documentation for the init_func in FuncAnimation could be interpreted to mean that it is called before every frame. At least that's how I interpreted until I tested.

More importantly, in the case when blit == True, if the init function doesn't return an iterable you get quite an opaque exception thrown.