Level Up 2: Knows the cases where comments are really necessary

gistfile1.txt

So, I lied above obviously. Sometimes comments are actually necessary.
Name (and defend) some cases where you should add comments to your code.

1. Comments that are intended to be compiled into public API documentation; using
   rDoc, for instance.

2. Rescue an exception that causes nothing to happen. A comment
is needed to explain why this is necessary, because it is expected
that something should happen when the exception is rescued. 
Although this can be alleviated by creating a method that is called
during the rescue. It's name will explain why nothing is supposed to happen.

3. Comments are sometimes needed in tests to explain edge cases.

4. Before writing code, comments are useful in writing pseudo-code. 
But once the code is written, these comments should be deleted.

5. Handling oddities of other people's libraries, or the Ruby
built-in library, that you have to code around.