Returns the list of qpoint indices equivalent (meaning they are the
        same frac coords) to the given one.

        Args:
            index: the qpoint index

        Returns:
            a list of equivalent indices

        TODO: now it uses the label we might want to use coordinates instead
        (in case there was a mislabel)

def get_equivalent_qpoints(self, index):
        """
        Returns the list of qpoint indices equivalent (meaning they are the
        same frac coords) to the given one.

        Args:
            index: the qpoint index

        Returns:
            a list of equivalent indices

        TODO: now it uses the label we might want to use coordinates instead
        (in case there was a mislabel)
        """
        #if the qpoint has no label it can"t have a repetition along the band
        #structure line object

        if self.qpoints[index].label is None:
            return [index]

        list_index_qpoints = []
        for i in range(self.nb_qpoints):
            if self.qpoints[i].label == self.qpoints[index].label:
                list_index_qpoints.append(i)

        return list_index_qpoints