handlers are not uniquely identified by their name. only within the
logger to which they are attached is their name unique. this function
is here to allow you grab a handler from a logger so you can examine
and alter it.
typical use of this function is in setLevel(newLevel, getHandler(...)).
Usage
getHandler(handler, logger='')
Arguments
handler
the name of the handler, or its action.
logger
optional: the name of the logger. defaults to the root logger.
