@classmethod
def createFromToken(cls, token, context=None, onMissingClass=None):
    """
        Create a serializable instance from an arbitrary storage token
        @param token: Storage token
        @param context: Mutable context for the loading process
        """
    anId = token.getId()
    if context and anId in context:
        instance = context[anId]
    else:
        classId = token.getClassId()
        aClass = cls._getFactoryClass(classId)
        if aClass is not None:
            instance = aClass()
            instance.initializeFromToken(token, context)
        else:
            if onMissingClass is None:
                onMissingClass = cls.defaultOnMissingClass
            instance = onMissingClass(token)
    return instance
