def create_entities_dict(name, face_entity_list, solid_entity_list, main_object=None):
    """
    Helper method for creating an entities dictionary.

    :param name: name of the collection of entities 
    :param face_entity_list: [face_entity_1, ..., face_entity_n]
    :param solid_entity_list: [solid_entity_1, ..., solid_entity_n]
    :param main_object: main object (usually a solid when the entity only has one)
    :return: entities_dict
    """
    entities_dict = {
            'name':name,
            'faces':face_entity_list,
            'solids':solid_entity_list,
            'main object':main_object
            }
    return entities_dict