How did Harry close the witch?

[SnapesSlytherin at aol.com]

No: HPFGUIDX 57577

On page 276 of PoA (American):
     Harry quickly pulled out his wand, muttered, "Dissendium!" and shoved 
his bag into the statue, but before he could climb in himself, Neville came 
around the corner.
     "Harry!  I forgot you weren't going to Hogsmeade either!"
     "Hi, Neville," said Harry, moving swiftly away from the statue and 
pushing the map back into his pocket.  "What are you up to?"
     <snip superfluous conversation between Harry and Neville>
     <snip Snape's entrance>
     Harry and Neville set off without another word.  As they turned the 
corner, Harry looked back.  Snape was running one of his hands over the 
one-eyes witch's head, examining it closely.

My question is: how did the witch's hump close?  Harry puts his bag in, and 
then Neville comes.  Does the door just shut itself after a few minutes?  Or 
does someone have to shut it themselves?

~*~*~Oryomai~*~*~


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