Secondary customization point, called from getFromKwargs to turn
           a validated value into a single property value

def parse_from_args(self, l):
        """Secondary customization point, called from getFromKwargs to turn
           a validated value into a single property value"""
        if self.multiple:
            return [self.parse_from_arg(arg) for arg in l]
        return self.parse_from_arg(l[0])