class_docstr: A node visitor that converts unchanged top-level statements to
  STANDALONE_COMMENT.
  
  This is used in addition to _convert_unchanged_line_by_line, to
  speed up formatting when there are unchanged top-level
  classes/functions/statements.
code: def __init__(self, lines_set: Set[int]):
      self._lines_set = lines_set
  
imports: import difflib
  from dataclasses import dataclass
  from typing import Collection, Iterator, List, Sequence, Set, Tuple, Union
  from black.nodes import LN, STANDALONE_COMMENT, Leaf, Node, Visitor, first_leaf, furthest_ancestor_with_last_leaf, last_leaf, syms
  from blib2to3.pgen2.token import ASYNC, NEWLINE
label_desc: Use image node_id 1 to create a new _TopLevelStatementsVisitor object from inherited base classes: Visitor with example: obj = _TopLevelStatementsVisitor(lines_set)