Duration operator ~/(int quotient)

Divides this Duration by the given quotient and returns the truncated result as a new Duration object.

Throws an IntegerDivisionByZeroException if quotient is 0.

Source 

Duration operator ~/(int quotient) {
  // By doing the check here instead of relying on "~/" below we get the
  // exception even with dart2js.
  if (quotient == 0) throw new IntegerDivisionByZeroException();
  return new Duration._microseconds(_duration ~/ quotient);
}