def nr_cases(self, institute_id=None):
query = {}<EOL>if institute_id:<EOL><INDENT>query['<STR_LIT>'] = institute_id<EOL><DEDENT>LOG.debug("<STR_LIT>".format(query))<EOL>nr_cases = self.case_collection.find(query).count()<EOL>return nr_cases<EOL>
Return the number of cases

        This function will change when we migrate to 3.7.1

        Args:
            collaborator(str): Institute id

        Returns:
            nr_cases(int)