- /Two argument addition of raw slices:
a += b 
- Divide a two digit numerator by a one digit divisor, returns quotient and remainder: 
- Uses the lehemer algorithm.
Based on https://github.com/golang/go/blob/master/src/math/big/int.go#L612
If - extendedis set, the Bezout coefficients are calculated, otherwise they are- None.
 
- Find last set bit
fls(0) == 0, fls(u32::MAX) == 32 
- Divide two integers, and ceil the result. 
- Jacobi returns the Jacobi symbol (x/y), either +1, -1, or 0.
The y argument must be an odd integer. 
- Three argument multiply accumulate:
acc += b * c 
- Three argument multiply accumulate:
acc += b * c 
- Calculate the modular inverse of - g.
Implementation is based on the naive version from wikipedia.
 
- Subtract with borrow: 
- XGCD sets z to the greatest common divisor of a and b and returns z.
If extended is true, XGCD returns their value such that z = ax + by.