code: def register_extensions(self, exts, force=False):
          
          for ext_in, ext_out in exts.items():
              self.register_extension(ext_in, ext_out, force)
docs: Add/register extensions.
  
          Args:
              exts (dict):
              force (bool): If ``force`` is set to ``True``, simply overwrite existing extensions, otherwise do nothing.
                  If the ``logger`` is set, log a warning about the duplicate extension if ``force == False``.