@staticmethod
def get_frozen(f):
    """Returns a string interpretation of the number of frozen/unfrozen layers in tuple `f`"""
    if f[0] == 0:
        return 'Unfrozen'
    elif f[1] == 0:
        return 'Frozen'
    else:
        return f'{f[0]}/{f[0] + f[1]} layers frozen'
