Return filenames for package's data files in 'src_dir

def find_data_files(self, package, src_dir):
        """Return filenames for package's data files in 'src_dir'"""
        patterns = self._get_platform_patterns(
            self.package_data,
            package,
            src_dir,
        )
        globs_expanded = map(glob, patterns)
        # flatten the expanded globs into an iterable of matches
        globs_matches = itertools.chain.from_iterable(globs_expanded)
        glob_files = filter(os.path.isfile, globs_matches)
        files = itertools.chain(
            self.manifest_files.get(package, []),
            glob_files,
        )
        return self.exclude_data_files(package, src_dir, files)