def intro_interps(toc, reg_part):
    """Logic to fill in any introduction headers for the entire
    interpretations. Note that at some point, we might have headers randomly
    appear elsewhere in the interpretations, unrelated to a specific
    section. That's a @todo."""
    elements = []
    for el in toc.get(reg_part + '-Interp', []):
        if el['index'][1] == 'Interp':
            elements.append({'label': 'Interpretations', 'sub_label': el[
                'title'], 'index': el['index'], 'section_id': '-'.join(el[
                'index'])})
    return elements
