Read the passage from A Doll’s House. [SCENE: A room furnished comfortably and tastefully, but not extravagantly. At the back, a door to the right leads to the entrance-hall, another to the left leads to Helmer's study. Between the doors stands a piano. In the middle of the left-hand wall is a door, and beyond it a window. Near the window are a round table, arm-chairs and a small sofa. In the right-hand wall, at the farther end, another door; and on the same side, nearer the footlights, a stove, two easy chairs and a rocking-chair; between the stove and the door, a small table. Engravings on the walls; a cabinet with china and other small objects; a small book-case with well-bound books. The floors are carpeted, and a fire burns in the stove. It is winter. A bell rings in the hall; shortly afterwards the door is heard to open. Enter NORA, humming a tune and in high spirits. She is in outdoor dress and carries a number of parcels; these she lays on the table to the right. She leaves the outer door open after her, and through it is seen a porter who is carrying a Christmas Tree and a basket, which he gives to the maid who has opened the door.] Nora: Hide the Christmas Tree carefully, Helen. Be sure the children do not see it until this evening, when it is dressed. [To the porter, taking out her purse.] How much? Why does the author of the play include the first paragraph of stage directions?