Creates a pymatgen PhononBandStructure from a band.yaml file.
    The labels will be extracted from the dictionary, if present.
    If the 'eigenvector'  key is found the eigendisplacements will be
    calculated according to the formula:
    \\exp(2*pi*i*(frac_coords \\dot q) / sqrt(mass) * v
     and added to the object.

    Args:
        bands_path: path to the band.yaml file
        has_nac: True if the data have been obtained with the option
            --nac option. Default False.
        labels_dict: dict that links a qpoint in frac coords to a label.

def get_ph_bs_symm_line(bands_path, has_nac=False, labels_dict=None):
    """
    Creates a pymatgen PhononBandStructure from a band.yaml file.
    The labels will be extracted from the dictionary, if present.
    If the 'eigenvector'  key is found the eigendisplacements will be
    calculated according to the formula:
    \\exp(2*pi*i*(frac_coords \\dot q) / sqrt(mass) * v
     and added to the object.

    Args:
        bands_path: path to the band.yaml file
        has_nac: True if the data have been obtained with the option
            --nac option. Default False.
        labels_dict: dict that links a qpoint in frac coords to a label.
    """
    return get_ph_bs_symm_line_from_dict(loadfn(bands_path), has_nac,
                                         labels_dict)