Fix return type of Ds\Sequence#copy()

[MidnightDesign]

I don't know why the return type isn't correctly inferred. It seems fine to me. Any ideas?

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[ondrejmirtes]

The method probably isn't declared on Sequence. The correct solution might be to write @return static above Collection::copy().

[MidnightDesign]

I've tried removing copy() from Sequence and making the return type of Collection static<TKey, TValue>, but that didn't change anything. I think it can't work because Collection takes two type arguments, and Sequence takes just one. I have no idea how to fix this.

[ondrejmirtes]

Try just static

[MidnightDesign]

You're right, that works. Thank you for your help!

[phpstan-bot]

This pull request has been marked as ready for review.

[ondrejmirtes]

Thank you!