def phasename(phaseID):
    """
    Take a phase ID and return the name of the phase.

    Parameters
    ------------
    phaseID : :class:`str`
        ID for the particular phase (e.g. 'olivine_0')

    Returns
    --------
    :class:`str`
        Name of the phase.
    """
    if phaseID.find('_') > 0:
        n = phaseID[:phaseID.find('_')]
    else:
        n = phaseID
    return n
