"A file containing 'a list of arrays?'" How can this be? Prithee, what does this mysterious file look like?

Forsooth ... ;-) ... in that will you find your answer!

Aww, alright, let me be a little bit less "cute" and a little bit more informative. The bottom-line question here is, after all, "what does this file of yours look like?" Byte-by-byte, what does it actually contain? Because after all, that is the only thing that any computer-program on the planet will ultimately have to deal with: the bytes themselves.