Returns the rendered release notes from all parsers as a string

def render(self):
        """ Returns the rendered release notes from all parsers as a string """
        release_notes = []
        for parser in self.parsers:
            parser_content = parser.render()
            if parser_content is not None:
                release_notes.append(parser_content)
        return u"\r\n\r\n".join(release_notes)