By default, R loads files in alphabetical order. Unfortunately not every
alphabet puts letters in the same order, so you can't rely on alphabetic
ordering if you need one file loaded before another. (This usually doesn't
matter but is important for S4, where you need to make sure that classes are
loaded before subclasses and generics are defined before methods.).
You can override the default alphabetical ordering with @include before.R,
which specify that before.R must be loaded before the current file.
Generally, you will not need to run this function yourself; it should be
run automatically by any package that needs to load your R files in
collation order.