Python message format based on message logging level in Python 3

logger.py

# Tested with Python 3.5.2

from config import LOGLEVEL
import logging

class SrvLogFormat(logging.Formatter):

    err_fmt  = "[E] %(msg)s"
    warn_fmt  = "[!] %(msg)s"
    dbg_fmt  = "[D] %(module)s: %(lineno)d: %(msg)s"
    info_fmt = "%(msg)s"

    def format(self, record):
        original_style = self._style

        if record.levelno == logging.DEBUG:
            self._style = logging.PercentStyle(self.dbg_fmt)
        if record.levelno == logging.INFO:
            self._style = logging.PercentStyle(self.info_fmt)
        if record.levelno == logging.WARNING:
            self._style = logging.PercentStyle(self.warn_fmt)
        if record.levelno == logging.ERROR:
            self._style = logging.PercentStyle(self.err_fmt)

        result = logging.Formatter.format(self, record)
        self._style = original_style
        return result

numeric_level = getattr(logging, LOGLEVEL.upper(), None)
if not isinstance(numeric_level, int):
    raise ValueError('Invalid log level: %s' % loglevel)

hdlr = logging.StreamHandler()
hdlr.setFormatter(SrvLogFormat())
logging.root.addHandler(hdlr)
logging.root.setLevel(numeric_level)