I didn't know if it was appropriate here to convert this to be able to read the value of ```@files``` - so i just created a new method for ```files``` which allows the ability to read or set.

If you don't think the new method is needed then I guess we can just do:
```
def file(val=NULL_ARG)
  @files << val unless val.equal?(NULL_ARG)
  @files
end
```
and then nuke the other method.  I'm not sure which is the best.