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Runs a function on every element and returns a new array of the results.
Calls the provided callback once for each element, collects the return values into a new array of the same length. Does not mutate the original. The callback receives (element, index, array).
A functor operation: maps a function over a container's values. In category theory terms, Array is a functor and .map is its fmap. Equivalent to a for-of loop with push, but declarative.