@yatsukhnenko I wasn't really sure the best way to handle the new option.

This way is flexible, but I wonder if we should instead take an options array for future-proofing (e.g. if Redis adds more exotic options to this command).

@michael-grunder currently in set and zadd commands we use array to handle NX/EX/etc options so maybe it worth to implement it here but I'm totally fine with current implementation.

@yatsukhnenko I added a check on the mode argument and updated our stubs/docs with actual documentation.

I think maybe we should break this command in PhpRedis 6.0.0 to instead return an integer (0 when an expiration was not set, 1 when an expiration was set, and false on failure).