You may remember that right at the end of December, OnePlus started rolling out OxygenOS 4.0, essentially Android 7.0 Nougat, for the OnePlus 3 and 3T. And you’d be completely correct. However, this was halted after 4.0 was found to be buggy and unstable for the OnePlus 3T.
[Update: Full ROMs available] OxygenOS 4.0.2 (Nougat) begins rolling out to OnePlus 3T was written by the awesome team at Android Police.