def _mark_transition_type(lookup_dict, lulc_from, lulc_to):
    """Mark transition type, given lulc_from and lulc_to.

    Args:
        lookup_dict (dict): dictionary of lookup values
        lulc_from (int): lulc code of previous cell
        lulc_to (int): lulc code of next cell

    Returns:
        carbon (str): direction of carbon flow
    """
    from_is_habitat = \
        lookup_dict[lulc_from]['is_coastal_blue_carbon_habitat']
    to_is_habitat = \
        lookup_dict[lulc_to]['is_coastal_blue_carbon_habitat']

    if from_is_habitat and to_is_habitat:
        return 'accum'  # veg --> veg
    elif not from_is_habitat and to_is_habitat:
        return 'accum'  # non-veg --> veg
    elif from_is_habitat and not to_is_habitat:
        return 'disturb'  # veg --> non-veg
    else:
        return 'NCC'