Mock logger object with auto function and label generation

print_logger.py

class Singleton(object):
    ''' singleton class only allows for one instantiation per python interpreter '''
    _instance = None
    def __new__(class_, *args, **kwargs):
        ''' override __new__ behavior to only return new instance if not previously instantiated '''
        if not isinstance(class_._instance, class_):
            class_._instance = object.__new__(class_, *args, **kwargs)
        return class_._instance

class PrintLogger(Singleton):
    ''' class that mimics logging module syntax '''
    _labels = ['debug', 'info', 'warn', 'error']
    def __init__(self):
        ''' dynamically creates functions corresponding with each label '''
        for _label in PrintLogger._labels:
            setattr(self, _label, self._mk_func(_name=_label))

    @classmethod
    def _mk_func(self, _name="log"):
        ''' returns a logging function with a dynamically generated signature/label '''
        def _log_function(msg="", _label=_name):
            print("[%s] %s" % (_label.upper(), msg))
        _log_function.__name__ = _name
        return _log_function

log = PrintLogger()

if __name__=="__main__":
    log = PrintLogger()
    log.debug("Oh hi!")
    log.info("Isn't this nice?")
    log.warn("But you should knock it off...")
    log.error("WE HAVE WORK TO DO!")

### Example output ###
## [DEBUG] oh hi!
## [INFO] isn't this nice.
## [WARN] but you should knock it off...
## [ERROR] WE HAVE WORK TO DO!