Function open_syncmers 

pub const fn open_syncmers(
    k: usize,
    w: usize,
) -> Builder<'static, false, NtHasher<false>, (), 2>

Return positions/values of open syncmers of length k+w-1.

These are windows with the minimizer in the middle of the window. This requires w to be odd.

k here corresponds to s in original syncmer notation: the minimizer length. k+w-1 corresponds to k in original syncmer notation: the length of the extracted string.