def create_spline_parameters(areas, vaccination_states_removed, leave_out="last"):
    """Generate dictionary with information for the actual spline parameter
    that is passed to :func: `model_vaccination_create_sbml`.

    Parameters
    ----------
    areas : list
        Names of areas for which splines are created.

    vaccination_states_removed : list
        Names of vaccines for which splines are created.

    leave_out : {'last', str, None}
        Name of area for which no spline should be computed. If 'last' the last
        area from the list areas is left out. We need to leave on area out
        such that the last area becomes one minus the sum of all other areas.

    Returns
    -------
    spline_parameters : dict
        Dicitionary containing the information of that is passed to
        :func: `model_vaccination_create_sbml`.
    """

    if leave_out == "last":
        areas_to_use = areas[:-1]
    elif leave_out is None:
        areas_to_use = areas
    else:
        areas_to_use = leave_out

    spline_parameters = {}
    for index_areas in areas_to_use:
        for index_vaccine in vaccination_states_removed:
            parameter_name = f"spline_{index_areas}_{index_vaccine}"
            spline_parameters[parameter_name] = {"value": 0, "constant": False}

    return spline_parameters