def main():
    # arrows = [{'from': 1, 'to': 0}, {'from': 2, 'to': 1}, {'from': 2, 'to': 4}, {'from': 2, 'to': 5},
    #           {'from': 4, 'to': 3}]
    # lines = pretty_tree_horizontal(arrows)
    # print('\n'.join(lines))
    # print('\n'.join([
    #     '◄─┐',
    #     '  │',
    #     '  ├►',
    #     '  │',
    #     '◄─┘',
    # ]))
    print('\n'.join(render_span(7, 12)))