def _process_cls_init(obj):
    """Set the following instance attributes with None or empty values
    (proper values will be set later at model creation):

    __xsimlab_model__ : obj
        :class:`Model` instance to which the process instance is attached.
    __xsimlab_name__ : str
        Name given for this process in the model.
    __xsimlab_state__ : dict or object
        Simulation active data store.
    __xsimlab_state_keys__ : dict
        Dictionary that maps variable names to their corresponding key
        (or list of keys for group variables) in the active store.
        Such keys consist of pairs like `('foo', 'bar')` where
        'foo' is the name of any process in the same model and 'bar' is
        the name of a variable declared in that process.
    __xsimlab_od_keys__ : dict
        Dictionary that maps variable names to the location of their target
        on-demand variable (or a list of locations for group variables).
        Locations are tuples like state keys.

    """
    obj.__xsimlab_model__ = None
    obj.__xsimlab_name__ = None
    obj.__xsimlab_state__ = None
    obj.__xsimlab_state_keys__ = {}
    obj.__xsimlab_od_keys__ = {}
