toUint256 method
Zero/sign extending cast to 256 bits.
Negative numbers are sign extended: -1 -> 0xffff...ffff
Positive numbers are zero extended.
Implementation
Uint256 toUint256() {
final ext = isNegative ? Uint64.max : Uint64.zero;
return Uint256.unsafe(ext, ext, _bits.hi, _bits.lo);
}