old_contents: import pytest
  from katana.trie import Trie
  
  
  @pytest.fixture
  def trie():
      return Trie([
          '1',
          '12',
          '123',
          '1234',
      ])
  
  
  def ls(*s):
      return [list(k) for k in s]
  
  
  def test_trie_pos(trie):
      assert trie.pos('1') == ls('1', '12', '123', '1234')
      assert trie.pos('12') == ls('12', '123', '1234')
      assert trie.pos('123') == ls('123', '1234')
      assert trie.pos('1234') == ls('1234')
  
new_contents: import pytest
  from katana.trie import Trie
  
  
  @pytest.fixture
  def trie():
      return Trie([
          '1',
          '12',
          '123',
          '1234',
      ])
  
  
  def ls(*s):
      return [list(k) for k in s]
  
  
  def test_trie_pos(trie):
      assert trie.pos('1') == ls('1', '12', '123', '1234')
      assert trie.pos('12') == ls('12', '123', '1234')
      assert trie.pos('123') == ls('123', '1234')
      assert trie.pos('1234') == ls('1234')
  
  
  def test_trie_insert(trie):
      trie.insert('456')
      assert trie.pos('456') == ls('456')
  
subject: Test Trie.insert method