I use IRB to explore.  Very often I type a.methods.sort, to see what an
object can do.  The problem is, you're hit with 100 methods from Object
(or the superclass).

I've experimented with:
a.methods - a.class.superclass.methods
which works well for simple things

but it doesn't seem to handle cases when there are a lot of included
modules.   Any ideas on how to see the methods defined in a.class only,
and not in any superclass or included module?