Clear a split string

Somewhat of an odd question but to improve memory performance I prefer re-using the same variable.
However, I want to make sure a split string is cleared before logic kicks in.
So I use this code:
tempstr = myreader.item("csvfield")
tempsplit = split(tempstr, ",")
But then want to reuse tempsplit again for:
tempstr = myreader.item("csvfield2")
tempsplit = split(tempstr, ",")
 How do I "clear" tempsplit before populating it with csvfield2?
Thanks.

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