static function retrieveFromPool($pk_value) {
		if (!static::$_poolEnabled || null === $pk_value) {
			return null;
		}

		$pk_value = (string) $pk_value;
		if (isset(static::$_instancePool[$pk_value])) {
			return static::$_instancePool[$pk_value];
		}

		return null;
	}
static function retrieveFromPool($pk_value) {
		if (!static::$_poolEnabled || null === $pk_value) {
			return null;
		}

		$pk_value = (string) $pk_value;
		if (isset(static::$_instancePool[$pk_value])) {
			return static::$_instancePool[$pk_value];
		}

		return null;
	}
static function retrieveFromPool ( $ pk_value ) { if ( ! static :: $ _poolEnabled || null === $ pk_value ) { return null ; } $ pk_value = ( string ) $ pk_value ; if ( isset ( static :: $ _instancePool [ $ pk_value ] ) ) { return static :: $ _instancePool [ $ pk_value ] ; } return null ; }
Return the cached instance from the pool.

@param mixed $pk_value Primary Key
@return static
Return the cached instance from the pool .