class tree:
    def __init__(self, x, c = []):
        self.label = x
        self.children = []
        for i in c:
            self.children.append(i)

    def __str__(self):
        h = '__'
        d = '|'
        f = '+'
        t = 'L'
        # if your terminal support UTF8, you can uncomment the following lines
        # and get a prettier picture.
        # t = '└'
        # f = '├'
        # d = '│'
        # h = '──'
        lh = len(h)
        r = ['a']
        r.append(f + h + ' b')
        r.append(d + ' ' * (lh + 1) + t + h + ' c')
        r.append(t + h + ' c')
        r.append(' ' + ' ' * (lh + 1) + f + h + ' d')
        r.append(' ' + ' ' * (lh + 1) + t + h + ' e')
        r.append(' ' + ' ' * (lh + 1) + ' ' + ' ' * lh + ' ' + t + h + ' f')
        return '\n'.join(r)

if __name__ == "__main__":
  x = tree('a', [tree('b', [tree('c')]), tree('c', [tree('d'), tree('e', [tree('f')])])])
  print(x)