Return the `c:dLbl` element representing the label for the data point
        at offset *idx* in this series, or |None| if not present.

def get_dLbl(self, idx):
        """
        Return the `c:dLbl` element representing the label for the data point
        at offset *idx* in this series, or |None| if not present.
        """
        dLbls = self.dLbls
        if dLbls is None:
            return None
        return dLbls.get_dLbl_for_point(idx)