I’m running the following program:

print(fget(12))
fset(12,1,true)
print(fget(12))
fset(12,2,false)
print(fget(12))

And the output is:

0
2
6

My understanding of the documentation (“v is boolean and can be true or false”) is that the second fset() call should unset the bit, not set it.

yep, known bug. i think zep has fixed this for the next version.