code: def _update_sub_repo(self, path, ignore_trie: Trie):
      from dvc.repo import Repo
  
      if path == self.root_dir:
          return
  
      dvc_dir = self.fs.join(path, Repo.DVC_DIR)
      if not self.fs.exists(dvc_dir):
          return
  
      root, dname = self.fs.split(path)
      key = self._get_key(root)
      pattern_info = PatternInfo(f"/{dname}/", f"in sub_repo:{dname}")
      new_pattern = DvcIgnorePatterns([pattern_info], root, self.fs.sep)
      old_pattern = ignore_trie.longest_prefix(key).value
      if old_pattern:
          plist, prefix = merge_patterns(
              self.fs.flavour,
              old_pattern.pattern_list,
              old_pattern.dirname,
              new_pattern.pattern_list,
              new_pattern.dirname,
          )
          ignore_trie[key] = DvcIgnorePatterns(
              plist, prefix, self.fs.sep
          )
      else:
          ignore_trie[key] = new_pattern
  
imports: import os
  import re
  from collections import namedtuple
  from itertools import chain, groupby, takewhile
  from typing import TYPE_CHECKING, List, Optional
  from pathspec.patterns import GitWildMatchPattern
  from pathspec.util import normalize_file
  from pygtrie import Trie
  from dvc.fs import Schemes, localfs
  from dvc.log import logger
  from dvc.pathspec_math import PatternInfo, merge_patterns
label_desc: Use image node_id 5 for calling the DvcIgnoreFilter obj's underlying member method code with example usage: obj._update_sub_repo(path, ignore_trie) without return types