Opens all available spreadsheets.

        :param title: (optional) If specified can be used to filter
                      spreadsheets by title.
        :type title: str

        :returns: a list of :class:`~gspread.models.Spreadsheet` instances.

def openall(self, title=None):
        """Opens all available spreadsheets.

        :param title: (optional) If specified can be used to filter
                      spreadsheets by title.
        :type title: str

        :returns: a list of :class:`~gspread.models.Spreadsheet` instances.

        """
        spreadsheet_files = self.list_spreadsheet_files()

        return [
            Spreadsheet(self, dict(title=x['name'], **x))
            for x in spreadsheet_files
        ]