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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def _find_longest_parent_path(path_set, path):
 """Finds the longest "parent-path" of 'path' in 'path_set'. This function takes and returns "path-like" strings which are strings made of strings separated by os.sep. No file access is performed here, so these strings need not correspond to actual files in some file-system.. This function returns the longest ancestor path For example, for path_set=["/foo/bar", "/foo", "/bar/foo"] and path="/foo/bar/sub_dir", returns "/foo/bar". Args: path_set: set of path-like strings -- e.g. a list of strings separated by os.sep. No actual disk-access is performed here, so these need not correspond to actual files. path: a path-like string. Returns: The element in path_set which is the longest parent directory of 'path'. """

  # This could likely be more efficiently implemented with a trie
  # data-structure, but we don't want to add an extra dependency for that.
  while path not in path_set:
    if not path:
      return None
    path = os.path.dirname(path)
  return path