public function exists($key)
	{
		$key = $this->normalizeKey($key);

		return array_key_exists($key, $this->items);
	}
public function exists($key)
	{
		$key = $this->normalizeKey($key);

		return array_key_exists($key, $this->items);
	}
public function exists ( $ key ) { $ key = $ this -> normalizeKey ( $ key ) ; return array_key_exists ( $ key , $ this -> items ) ; }
Test whether an item of given key exists

@param  string $key Item's key
@return bool        Whether this key exists in this collection
Test whether an item of given key exists