At...
Why are we using anonymous module here? Because we want to stay in the same context, so we can use the prepend variable.
and...
prepend doesn’t exist in the context of the new method, since it’s a local variable. We have to define a method dynamically to use it.
.. maybe better to mention that by defining the module and the method in a block, we stay in the same lexical [closure](http://en.wikipedia.org/wiki/Closure_(computer_science\)), and in that way we can access the local variables. What I'm trying to say is that we don't need to define these things anonymously or dynamically; we just need to define them in a the same lexical closure, and we achieve that by using blocks.
\o\
Thank you, nice one. Agreed completely. I'll add your note. ❤️