Returns the first ICachableItem in the ICachableSource

def first(self):
        """Returns the first ICachableItem in the ICachableSource"""
        # we need to create a new object to insure we don't corrupt the generator count
        csvsource = CSVSource(self.source, self.factory, self.key())
        try:
            item = csvsource.items().next()
            return item
        except StopIteration:
            return None