/**
* Returns an infinite, traversable sequence that exponentially grows by given percentage
*
* @param integer $start
* @param integer $percentage Integer between 1 and 100
* @return ExponentialSequence
* @throws InvalidArgumentException
*/
function sequence_exponential($start, $percentage)
{
InvalidArgumentException::assertIntegerGreaterThanOrEqual($start, 1, __METHOD__, 1);
InvalidArgumentException::assertIntegerGreaterThanOrEqual($percentage, 1, __METHOD__, 2);
InvalidArgumentException::assertIntegerLessThanOrEqual($percentage, 100, __METHOD__, 2);
return new ExponentialSequence($start, $percentage);
}