Adds more than one document using the same API call

        Returns two lists: the first one contains the successfully uploaded
        documents, and the second one tuples with documents that failed to be
        uploaded and the exceptions raised.

def add_documents(self, documents):
        '''
        Adds more than one document using the same API call

        Returns two lists: the first one contains the successfully uploaded
        documents, and the second one tuples with documents that failed to be
        uploaded and the exceptions raised.
        '''
        result, errors = [], []
        for document in documents:
            try:
                result.append(self.add_document(document))
            except RuntimeError as exc:
                errors.append((document, exc))

        return result, errors