Other symbols i have seen used for is defined to be equal to are three horizontal lines instead of two, and $=$ with either a triangle or. Maybe instead of handling your example, because the context is not always relevant, let's look at possible groupings of the symbols. After looking at the wikipedia article on topological space, i still cannot grasp intuitively what topological space is.
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I have encountered this when referencing subsets and vector subspaces. For example, t span(s) should mean that t is. For example, if we are.