code: def trunk(self, unique=True):
          
          # uniqueness is not correct in `trunk` yet
          unique = False
          res = []
          if self.children:
              if self.name is not None:
                  res.append(self)
              for child in self.children:
                  for sub_child in child.trunk(unique=unique):
                      if not unique or sub_child not in res:
                          res.append(sub_child)
          return res
docs: Get the trunk of the tree starting at this root.