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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def _set_logger(self):
 """change log format."""

        self.logger.propagate = False
        hdl = logging.StreamHandler()
        fmt_str = '[querier][%(levelname)s] %(message)s'
        hdl.setFormatter(logging.Formatter(fmt_str))
        self.logger.addHandler(hdl)