code: def create_tree(self, parents, tree_phrases):
      n = len(parents)
      self.nodes = [None for i in range(n)]
      self.root = [None]
      for i in range(n):
          self.create_node(parents, i)
      for i, phrase in enumerate(tree_phrases):
          self.nodes[i].val = phrase
      for node in self.nodes:
          if node.val is None:
              node.val = " ".join((node.left.val, node.right.val))
  
imports: import os
  from typing import List, Optional, Set
  import pandas
  from ludwig.datasets.dataset_config import DatasetConfig
  from ludwig.datasets.loaders.dataset_loader import DatasetLoader
label_desc: Use image node_id 2 for calling the SSTTree obj's underlying member method code with example usage: obj.create_tree(parents, tree_phrases) without return types