I had read through a rails book and once found we can add # TODO: and some # stuff in codes, so we can you some rake cmd to look back.
My problems is I can't find where are those "# stuff" and "rake cmd" I google and search around, but can't find and don't know what keywords to search.
You can use # TODO, # FIXME, and # OPTIMIZE and you can easily get all of these with the following rake task: rake notes
In addition to the default annotations, you can always specify and search for your own annotations:
rake notes:custom ANNOTATION=ZOMG