public function exists($key) {
		return isset($this->_data[$key]) || isset($this->registered[$key]);
	}
public function exists($key) {
		return isset($this->_data[$key]) || isset($this->registered[$key]);
	}
public function exists ( $ key ) { return isset ( $ this -> _data [ $ key ] ) || isset ( $ this -> registered [ $ key ] ) ; }
Checks whether an key can be resolved to an object or registered closure.

@param string $key Item key.

@return boolean True if the item can be resolved to an object.
Checks whether an key can be resolved to an object or registered closure .