method not found in class...

plz see my index.php in that when i write

var_dump($tasks[0]->foo());
it says under foo method not found in class..
and also in 

function fetchAll($conn)
{
    $statement = $conn->prepare('select * from todos');
    $statement->execute();
    return $statement->fetchAll(PDO::FETCH_CLASS, 'Task');
}
under prepare , fetchall

im new to phpstorm plz help me