operator ~/ method
Performs integer division on this BigRational by the given BigRational and returns the result as a BigRational.
other The divisor BigRational.
Returns a new BigRational representing the integer division of this BigRational by the given BigRational.
Implementation
BigRational operator ~/(BigRational other) {
  final BigInt divmod = _truncate;
  final BigInt rminder = _remainder;
  BigInt floor;
  if (rminder == _zero || !divmod.isNegative) {
    floor = divmod;
  } else {
    floor = divmod - _one;
  }
  return BigRational._(floor, _one);
}