old_contents: from render_block.base import render_block_to_string
  from render_block.exceptions import BlockNotFound, UnsupportedEngine
  
new_contents: from render_block.base import render_block_to_string
  from render_block.exceptions import BlockNotFound, UnsupportedEngine
  
  __all__ = ["BlockNotFound", "UnsupportedEngine", "render_block_to_string"]
  
subject: Fix flake8 errors.