Nagini: If she's not a Horcrux, what the heck is she?

[Lisa]

No: HPFGUIDX 171974

--- In HPforGrownups at yahoogroups.com, "k12listmomma" 

it seems to me that the Brazilian 
> Python was the snake at the zoo- the one Harry set on Dudley.
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Lisa:

No, I do have canon for that.  In SS, it specifically references that 
snake as a boa constrictor.

And Harry didn't set the snake on Dudley.  He unintentionally set the 
snake free; the snake didn't go after anyone.