code: def pprint(self, index=False, delimiter='-'):
          
          lines = _build_tree_string(self, 0, index, delimiter)[0]
          print('\n' + '\n'.join((line.rstrip() for line in lines)))
docs: Pretty-print the binary tree.
  
          :param index: If set to True (default: False), display level-order_
              indexes using the format: ``{index}{delimiter}{value}``.
          :type index: bool
          :param delimiter: Delimiter character between the node index and
              the node value (default: '-').
          :type delimiter: str | unicode
  
          **Example**:
  
          .. doctest::
  
              >>> from binarytree import Node
              >>>
              >>> root = Node(1)              # index: 0, value: 1
              >>> root.left = Node(2)         # index: 1, value: 2
              >>> root.right = Node(3)        # index: 2, value: 3
              >>> root.left.right = Node(4)   # index: 4, value: 4
              >>>
              >>> root.pprint()
              <BLANKLINE>
                __1
               /   \\
              2     3
               \\
                4
              <BLANKLINE>
              >>> root.pprint(index=True)     # Format: {index}-{value}
              <BLANKLINE>
                 _____0-1_
                /         \\
              1-2_        2-3
                  \\
                  4-4
              <BLANKLINE>
  
          .. note::
              If you do not need level-order_ indexes in the output string, use
              :func:`binarytree.Node.__str__` instead.
  
          .. _level-order:
              https://en.wikipedia.org/wiki/Tree_traversal#Breadth-first_search