I was going through the exercises in Ruby Koans and I was struck by the following Ruby quirk that I found really unexplainable:
array = [:peanut, :butter, :a
You need to be able to assign to those slices, so they are defined in such a way that the beginning and the end of the string have working zero-length expressions.
array[4, 0] = :sandwich array[0, 0] = :crunchy => [:crunchy, :peanut, :butter, :and, :jelly, :sandwich]