def get_farthest_leaf(self, topology_only=False, is_leaf_fn=None):
min_node, min_dist, max_node, max_dist = self._get_farthest_and_closest_leaves(<EOL>topology_only=topology_only, is_leaf_fn=is_leaf_fn)<EOL>return max_node, max_dist<EOL>
Returns node's farthest descendant node (which is always a leaf), and the
distance to it.

:argument False topology_only: If set to True, distance
  between nodes will be referred to the number of nodes
  between them. In other words, topological distance will be
  used instead of branch length distances.

:return: A tuple containing the farthest leaf referred to the
  current node and the distance to it.