Section 9 - Doorknob
The doorknob is part of the dining-hall door. The doorknob equals the umbrella. The description of the doorknob is "[if the doorknob is attached]The doorknob is a device for opening and closing the door.[otherwise]The knob used to be a part of the dining hall door."
Understand "knob" and "door knob" as the doorknob.
Definition: the doorknob is attached if it is part of the dining-hall door.
Instead of turning or pushing or pulling the attached doorknob:
try opening the dining-hall door.
Check taking the attached doorknob:
say "It's firmly attached to the door." instead.
After changing the doorknob into the attached umbrella: [1]
say "The doorknob sparkles and turns into an umbrella. The umbrella is now sticking out the door where the knob used to be."
Note
[1]. Testing for "attached doorknob" wouldn't work because at this stage it's not attached anymore. It has been replaced by the umbrella which in turn is attached to the door.