address tuple in collate

[michalozeryflato]

No description provided.

[YoelShoshan]

LGTM

I do hope, however, that it doesn't break any expected behavior.
Because until this change, I think that if people wanted collate to not touch their sequential, they could have used a tuple to express that (without using any additional instructions to the collate function).

[mosheraboh]

Thanks Michal.
It will break compatibility, I suggest to make it a custom function (so you can force it per key).
If you are ok with it, lets talk and I'll share more details.

[michalozeryflato]

I accepted the reviewers' comments and fixed the collate in bmfm-bio data modules. closing this PR.