Example: Log messages into different categories
By default, unsourced log messages get assigned to a "global" bucket.
Example: Log messages into different categories and assign them
to a source called myBucket
You can assign a source to a log message by passing it in as
the third argument to YAHOO.log().
Example: Create a LogWriter to write log messages from a class
named MyClass
If you plan to assign many log messages to the same source (such as from a class), it may be easier to write log messages from a LogWriter instance.