Convert from json/msgpack-friendly

def unpack(cls, val):
        '''
        Convert from json/msgpack-friendly
        '''
        reqdictf, incunitf, incval = val
        reqdict = {TimeUnit[k.upper()]: v for (k, v) in reqdictf.items()}
        incunit = None if incunitf is None else TimeUnit[incunitf.upper()]
        return cls(reqdict, incunit, incval)