def ltypeOfLaueGroup(tag):
    """
    Yield lattice type of input tag.

    Parameters
    ----------
    tag : TYPE
        DESCRIPTION.

    Raises
    ------
    RuntimeError
        DESCRIPTION.

    Returns
    -------
    ltype : TYPE
        DESCRIPTION.

    """
    if not isinstance(tag, str):
        raise RuntimeError("entered flag is not a string!")

    if tag.lower() == 'ci' or tag.lower() == 's2':
        ltype = 'triclinic'
    elif tag.lower() == 'c2h':
        ltype = 'monoclinic'
    elif tag.lower() == 'd2h' or tag.lower() == 'vh':
        ltype = 'orthorhombic'
    elif tag.lower() == 'c4h' or tag.lower() == 'd4h':
        ltype = 'tetragonal'
    elif tag.lower() == 'c3i' or tag.lower() == 's6' or tag.lower() == 'd3d':
        ltype = 'trigonal'
    elif tag.lower() == 'c6h' or tag.lower() == 'd6h':
        ltype = 'hexagonal'
    elif tag.lower() == 'th' or tag.lower() == 'oh':
        ltype = 'cubic'
    else:
        raise RuntimeError(
            "unrecognized symmetry group.  "
            + "See ''help(quatOfLaueGroup)'' for a list of valid options.  "
            + "Oh, and have a great day ;-)"
        )

    return ltype