'Called by the builder to initialize the template system.
*builder* is the builder object; you\'ll probably want to look at the
value of ``builder.config.templates_path``.
*theme* is a :class:`sphinx.theming.Theme` object or None; in the latter
case, *dirs* can be list of fixed directories to look for templates.'

def init(self, builder, theme=None, dirs=None):

    raise NotImplementedError('must    be    implemented    in    subclasses')
