Return the textual or numeric representation of logging level 'level'.
If the level is one of the predefined levels (CRITICAL, ERROR, WARNING,
INFO, DEBUG) then you get the corresponding string. If you have
associated levels with names using addLevelName then the name you have
associated with 'level' is returned.
If a numeric value corresponding to one of the defined levels is passed
in, the corresponding string representation is returned.
If a string representation of the level is passed in, the corresponding
numeric value is returned.
If no matching numeric or string value is passed in, the string
'Level %s' % level is returned.
3.4: In Python versions earlier than 3.4, this function could also be passed a text level, and would return the corresponding numeric value of the level. This undocumented behaviour was considered a mistake, and was removed in Python 3.4, but reinstated in 3.4.2 in order to retain backward compatibility.