Any idea how to download a small part of the chain for testing purposes? I am experimenting with Python and Rust libraries on my laptop. I don't actually want to get a node going on it and download the full chain; I just need some blocks to play with. 

I want to keep my question general enough though; what is the easiest way for someone to download just a small portion of the blockchain, given specific beginning and end points in block numbers? Are there any libraries that would do that either in Python, JS, or Rust (or any other languages, so my question applies to all developers)?
As far as I know, there is no way to download arbitrary blocks (although I suspect it's not too hard to do if you implement your own client).

If you just want blocks for testing, you won't have much trouble finding bootstrap.dats that contain a few hundred thousand blocks. Alternatively, you could just run bitcoin core for half an hour or so and get a few thousand blocks from the start of the chain - The early blocks are mostly empty and download pretty quick.