hold on until it's over

When the cab drove away from the door, Sara was sitting on the floor of her sitting-room, with her hands under her chin and her eyes following it until it had turned the corner of the square. Emily was sitting by her, and she looked after it, too. When Miss Minchin sent her sister, Miss Amelia, to see what the child was doing, she found she could not open the door.

'I have locked it,' said a queer, polite little voice from inside. 'I want to be quite by myself, if you please.'