I have a style question. With the old scipy/Numeric, when I had a vector I wanted to be an optional variable in a function I would set is default to "myvect=[]". Then when I wanted to test whether or not the variable had been specified, I just checked "if myvect:". With numpy arrays, this produces a message about ambiguous results for testing arrays and says I should use myvect.any(). The problem is that empty lists don't have an "any" method. I could set the optional arrays explicitly to None or I could check if it" ==[]", but both of these are slightly more fragile (if I accidentally pass an empty list instead of None it would cause problems). I could also set the optional array to "array([])" and always test "any()", but that is more typing. Is there a best way to handle optional arrays in function specifications? (I am slightly addicted to Python's boolean testing for empty objects.) Ryan