code: def _add_defaults_python(self):
          
          if self.distribution.has_pure_modules():
              build_py = self.get_finalized_command('build_py')
              self.filelist.extend(build_py.get_source_files())
              # This functionality is incompatible with include_package_data, and
              # will in fact create an infinite recursion if include_package_data
              # is True.  Use of include_package_data will imply that
              # distutils-style automatic handling of package_data is disabled
              if not self.distribution.include_package_data:
                  for _, src_dir, _, filenames in build_py.data_files:
                      self.filelist.extend([os.path.join(src_dir, filename)
                                            for filename in filenames])
docs: getting python files