def setOFFSET(self, value):
        # Basically the start of slicing. This can normally be a negative
        # number in python. For now (and probably forever), not supported.
        # i.e. my_list[-10:] is not supported
        if type(value) != int:
            raise RuntimeError("Can only slice with integer")
        if value < 0:
            raise RuntimeError("Slicing with negative index is not allowed")
        if self.OFFSET is None:
            self.OFFSET = value
        if self.OFFSET < value:
            self.OFFSET = value