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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 signed_raw(self) -> str: """ Return Revocation signed raw document string :return: """

        if not isinstance(self.identity, Identity):
            raise MalformedDocumentError("Can not return full revocation document created from inline")

        raw = self.raw()
        signed = "\n".join(self.signatures)
        signed_raw = raw + signed + "\n"
        return signed_raw