Searches for a given element and, if found, returns the corresponding key/index of that element. The comparison of two elements is strict, that means not only the value but also the type must match. For objects this means reference equality.
mixed $element The element to search for.:
mixed The key/index of the element or FALSE if the element was not found.
Overrides Collection::indexOf
public function indexOf($element) {
return array_search($element, $this->_elements, true);
}