Markdownのヘッダーをリストに変換して目次にする

gistfile1.txt

import sys

def header_to_list(s):
    header_level = 0
    for c in s:
        if c == '#':
            header_level += 1
        else:
            break
    ret = []
    if header_level > 0:
        if header_level > 1:
            ret.append('  ' * (header_level - 1))
        ret.append('-')
        ret.append(s[header_level:].strip('\n'))
    return ''.join(ret)


def main():
    fin = open(sys.argv[1], 'r', encoding='utf_8')
    lines = fin.readlines()
    fin.close()
    print('\n'.join([x for x in [header_to_list(line) for line in lines] if x]))

if __name__ == '__main__':
    main()