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Python

Posted by Jacob Brookhart
Jacob Brookhart
Courses Plus Student 6,765 Points

pres = pres or set()

So another newbie question... in this code challenge, the function is already populated with pres = pres or set. The default condition of pres = None. So why is it that this code selects an empty set (set()) instead of an empty variable? How is this hierarchy organized?

1 Answer

Steven Parker
Steven Parker
243,215 Points
Steven Parker
Steven Parker
243,215 Points

The value "None" is considered "falsey". So when "pres" is "None", then the code "pres = pres or set()" works the same as if it were just "pres = set()".

Jacob Brookhart
Jacob Brookhart
Courses Plus Student 6,765 Points

Any recommendation on where to find the documentation for this? It makes sense but I think I need to go into the semantics of it

Steven Parker
Steven Parker
243,215 Points
Steven Parker
Steven Parker
243,215 Points

You might look in the official Python documentation on Truth Value Testing and Boolean Operations.

Jacob Brookhart
Jacob Brookhart
Courses Plus Student 6,765 Points

Thank you!