We might have a terminology issue here, since according to Wikipedia
there is some dispute over whether or not to include the equality case
in subset/superset:
https://en.wikipedia.org/wiki/Subset
For what it is worth, I'm in the school that subset implies proper subset
[...]
Wikipedia's pedantry notwithstanding, I don't think this is a useful position *when talking about Python sets*, since Python's set's .issubset() method returns True when the argument is the same set:
>>> {1}.issubset({1})
True
Or did I miss a wink?