There is an undocumented (as of the last distributed docs,
anyway), IsOk(). item.IsOk() (where item is the returned
tree item) returns true if it's good, false, otherwise.
I believe that, according to some discussions here on this
list a few weeks ago, the current CSV versions and future
releases will return an invalid item that evaluates to False,
so you can do:
while item:
(i.e. valid items will all evaluate to true).
Al