code: def get_tree_depth( self ):
          ''' Finds depth of this tree. '''
          if (self.children):
              depth = 1
              childDepths = []
              for child in self.children:
                  childDepths.append( child.get_tree_depth() )
              return depth + max(childDepths)
          else:
              return f get_tree_depth( self ):
          ''' Finds depth of this tree. '''
          if (self.children):
              depth = 1
              childDepths = []
              for child in self.children:
                  childDepths.append( child.get_tree_depth() )
              return depth + max(childDepths)
          else:
              return 0
docs: Finds depth of this tree.