docs: def outliers(self, truncate=False):
          """
          Show 10 queries that have longest execution time in aggregate. Requires
          the pg_stat_statments Postgres module to be installed.
  
          Record(
              qry='UPDATE pgbench_tellers SET tbalance = tbalance + ?;',
              exec_time=datetime.timedelta(0, 19944, 993099),
              prop_exec_time='67.1%',
              ncalls='845589',
              sync_io_time=datetime.timedelta(0)
          )
  
          :param truncate: trim the Record.qry output if greater than 40 chars
          :returns: list of Records
          """
  
          if self.pg_stat_statement():
              if truncate:
                  query = """
                      CASE WHEN length(query) < 40
                          THEN query
                          ELSE substr(query, 0, 38) || '..'
                      END
                  """
              else:
                  query = 'query'
  
              return self.execute(sql.OUTLIERS.format(query=query))
          else:
              return [self.get_missing_pg_stat_statement_error()]