old_contents: """For backward compatibility, expose main functions from
  ``setuptools.config.setupcfg``
  """
  import warnings
  from functools import wraps
  from textwrap import dedent
  from typing import Callable, TypeVar, cast
  
  from .._deprecation_warning import SetuptoolsDeprecationWarning
  from . import setupcfg
  
  Fn = TypeVar("Fn", bound=Callable)
  
  __all__ = ('parse_configuration', 'read_configuration')
  
  
  def _deprecation_notice(fn: Fn) -> Fn:
      @wraps(fn)
      def _wrapper(*args, **kwargs):
          msg = f"""\
          As setuptools moves its configuration towards `pyproject.toml`,
          `{__name__}.{fn.__name__}` became deprecated.
  
          For the time being, you can use the `{setupcfg.__name__}` module
          to access a backward compatible API, but this module is provisional
          and might be removed in the future.
          """
          warnings.warn(dedent(msg), SetuptoolsDeprecationWarning)
          return fn(*args, **kwargs)
  
      return cast(Fn, _wrapper)
  
  
  read_configuration = _deprecation_notice(setupcfg.read_configuration)
  parse_configuration = _deprecation_notice(setupcfg.parse_configuration)
  
new_contents: """For backward compatibility, expose main functions from
  ``setuptools.config.setupcfg``
  """
  import warnings
  from functools import wraps
  from textwrap import dedent
  from typing import Callable, TypeVar, cast
  
  from .._deprecation_warning import SetuptoolsDeprecationWarning
  from . import setupcfg
  
  Fn = TypeVar("Fn", bound=Callable)
  
  __all__ = ('parse_configuration', 'read_configuration')
  
  
  def _deprecation_notice(fn: Fn) -> Fn:
      @wraps(fn)
      def _wrapper(*args, **kwargs):
          msg = f"""\
          As setuptools moves its configuration towards `pyproject.toml`,
          `{__name__}.{fn.__name__}` became deprecated.
  
          For the time being, you can use the `{setupcfg.__name__}` module
          to access a backward compatible API, but this module is provisional
          and might be removed in the future.
          """
          warnings.warn(dedent(msg), SetuptoolsDeprecationWarning, stacklevel=2)
          return fn(*args, **kwargs)
  
      return cast(Fn, _wrapper)
  
  
  read_configuration = _deprecation_notice(setupcfg.read_configuration)
  parse_configuration = _deprecation_notice(setupcfg.parse_configuration)
  
subject: Add stacklevel=2 to make calling code clear