Algorithm help per favore

[Skip Montanaro]

    David> It's tempting to use "not L[0]" instead (since what I want is an
    David> object that's not equal to L[0]) but that fails when L is empty.

How about "not L[0:1]"?  Since L is a sequence (right?), "not L[0:1]" will
be True if L is empty and False otherwise.

Skip