Fibonacci Sequence iterator, because hey... why not?

fibonacci_sequence_generator.php

<?php

class Fibonacci_Sequence implements Iterator {
	private $start;
	public function __construct($start=0){
		$this->start = $start;
	}
	public function current() {
		return round(
				(pow(((1 + sqrt(5)) / 2), $this->key) - pow((-1 / (1 + sqrt(5)) / 2), $this->key)) / sqrt(5)
		);
	}
	public function key() {
		return $this->key;
	}
	public function next() {
		$this->key++;
	}
	public function rewind() {
		$this->key = $this->start;
	}
	public function valid() {
		return true;
	}
}

$n = new Fibonacci_Sequence(10);

$i = 0;
foreach ($n as $value) {
	if ($i == 100) {
		break;
	}
	$i++;
	echo $value . PHP_EOL;
}