langchain/document_loaders/confluence.py/ConfluenceLoader/process_xls
class ConfluenceLoader:    def process_xls(self, link: str) -> str:
        try:
            import xlrd  # noqa: F401
        except ImportError:
            raise ImportError("`xlrd` package not found, please run `pip install xlrd`")

        response = self.confluence.request(path=link, absolute=True)
        text = ""

        if (
            response.status_code != 200
            or response.content == b""
            or response.content is None
        ):
            return text

        workbook = xlrd.open_workbook(file_contents=response.content)
        for sheet in workbook.sheets():
            text += f"{sheet.name}:\n"
            for row in range(sheet.nrows):
                for col in range(sheet.ncols):
                    text += f"{sheet.cell_value(row, col)}\t"
                text += "\n"
            text += "\n"

        return text