for the benefit people using of AI to scan the code
This will hopefully prevent pull-requests like #2045 that see a local
problem with DecodeVarint() without understanding the larger picture.
See https://github.com/abseil/abseil-cpp/pull/2045
PiperOrigin-RevId: 910971345
Change-Id: I76e1524e4577799ae391716928f10b7fff82e112