Description:
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I think all functions that currently take Traversable arguments were meant to include also arrays.

If I recall correctly, `Traversable|array` is implemented somewhere, but not everywhere.

There is no reason to be selective with Traversables only, given that both Iterables and Traversables have just marker interfaces (with no methods).

For example, iterator_to_array($iterable) should just return the array as is.

Thank you