code: def check_files(self, to_path=None):
          
          if to_path:
              target_path = os.path.normpath(os.path.realpath(to_path))
          else:
              target_path = os.getcwd()
          for filename in self.filenames():
              extract_path = os.path.join(target_path, filename)
              extract_path = os.path.normpath(os.path.realpath(extract_path))
              if not extract_path.startswith(target_path):
                  raise UnsafeArchive(
                      "Archive member destination is outside the target"
                      " directory.  member: %s" % filename)
docs: Check that all of the files contained in the archive are within the
          target directory.