The core of reveal_converter...

    def build(self):
        "build the slides structure from text list and delimiters"
        text = self.convert().split('\n')
        left = '<section>'
        right = '</section>'
        pre_body = [list(x[1]) for x in itertools.groupby(text,
            lambda x: x == u'delimiters') if not x[0]]
        #generation of slides as a list of list
        pre_slides = [list(x[1]) for x in itertools.groupby(pre_body[1],
            lambda x: x == u'slide_type = slide') if not x[0]]
        for slide in pre_slides:
            slide.insert(0, left)
            slide.append(right)
            # encapsulation of each nested slide
            if u'slide_type = subslide' in slide:
                slide.insert(0, left)
                slide.append(right)
            for i, j in enumerate(slide):
                if j == u'slide_type = subslide':
                    slide[i] = right + left
        slides = [pre_body[0]] + pre_slides[1:] + [pre_body[2]]
        return u'\n'.join(list(itertools.chain(*slides)))