code: def build_sdist(source_dir, sdist_dir, config_settings=None):
      
      if config_settings is None:
          config_settings = {}
      requires, backend = _load_pyproject(source_dir)
      hooks = Pep517HookCaller(source_dir, backend)
  
      with BuildEnvironment() as env:
          env.pip_install(requires)
          reqs = hooks.get_requires_for_build_sdist(config_settings)
          env.pip_install(reqs)
          return hooks.build_sdist(sdist_dir, config_settings)
docs: Build an sdist from a source directory using PEP 517 hooks.
  
      :param str source_dir: Source directory containing pyproject.toml
      :param str sdist_dir: Target directory to place sdist in
      :param dict config_settings: Options to pass to build backend
  
      This is a blocking function which will run pip in a subprocess to install
      build requirements.