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Changes between Initial Version and Version 1 of Ticket #16360, comment 4

initial	v1
46	46	I suppose you first check `if self._instance is not None` to avoid the performance hit of taking the lock; this optimization should be explained in a quick comment.
47	47
48		I think the whole function would be ~~more~~ easier to understand like this:
	48	I think the whole function would be easier to understand like this:
49	49
50	50	{{{