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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 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)