As Logan pointed out in a different thread:

> % cat increment.rb
> class Fixnum
>   def increment
>     self = self + 1
>   end
> end
>
> a = 1
> a.increment
>
>
> % ruby increment.rb
> -:13: Can't change the value of self
>     self = self + 1
>           ^

So, how WOULD I create an .increment operator? I get why I can't put it 
in class Fixnum (well, I think I know why); Fixnums are symbol-ish-ly 
unalterable. 5.increment should fail, for sanity's sake.

So I have to add .increment to class . . . hmm. I can't add it to 
variables; they're just references. But I want my_var.increment to 
change 'my_var' so that it references the next integer in line.

Strings have methods that alter strings in place, but a String object 
is a composite object, made up of characters, and !-type methods alter 
the characters of the string without altering the variable's reference. 
Numbers aren't composite objects. Maybe it can't be done? But people 
are constantly amazing me with crazy magical Ruby tricks; it seems so 
improbable that there isn't a way to do this as well . . .

Somebody else pointed out I could just my_var += 1. Yes, but to me, 
that implies that the "1" is deliberate, and at some other point I 
might add 2 or 5 or something, whereas using "inc" or "++" or whatever 
says "it really doesn't matter if I'm counting by ones, tens, Roman 
numerals, or letters. This variable is just stepping upwards."

But the main reason I'm asking is not to slightly improve the esthetics 
of a couple lines of code. I'm certain that I'm going to learn 
something interesting from the answer to the question.