def get_template_overrides(name):
    """(Optional) local changes to specific templates

        Return a sequence of tuples (old_html, new_html, function) where

         old_html::
           The name of the template overriden by this theme.
         new_html::
           The name of the template file replacing the former.
         function::
           Optional callback (or None) to add further data . Signature:
                   req::
                       Request object
                   template::
                       The value of `old_html` above
                   data::
                       Template data, may be modified
                   content_type::
                       Reported MIME type

        since 2.2.0
        """
