flask logging

https://www.jianshu.com/p/9f08c72a148b

Log output level

app.logger.debug('A value for debugging')
app.logger.warning('A warning occurred (%d apples)', 42)
app.logger.error('An error occurred')

Flask which is app instance, and this is a standard app.logger logging Logger, therefore, is consistent with our in use app.logger selectable output level defined in the python logging.