This works:

    $ rake

    $ bin/natalie --ast -e "p 1+2"
    s(:block, s(:block, s(:call, nil, :p, s(:call, s(:lit, 1), :+, s(:lit, 2)))))

    $ bin/natalie -e "p 1+2"
    3

I was trying to get test/natalie/method_test.rb parsing (and passing),
but I found a few unexpected results from YARP. I think these are bugs,
which I filed here:

ruby/prism#1435
ruby/prism#1436

I'd love to find a way to avoid these dependencies. These are just for
generating some sources for YARP, and are not used after that. I bet we
can pre-generate YARP sources and commit to our repo...

This reverts commit 671c9e4.

This might allow us to skip installing some gems with bundler during the
build process... I need to make sure this works across platforms.

Hash literal value omission wasn't added until 3.1 :-)

`rake clean` cleans up our own sources, but not external libraries like
YARP and Onigmo. If we need to rebuild external libraries, we can use
`rake clobber build`.

This returns a simpler node in a very specific case of "#{'str'}" which
gets one spec passing that relied on that.

We have to keep the sexp_type for symbol, regex, etc.

For now... once the test suite is passing, it would be good to come back
and remove this whole compatibility layer and have pass1.rb just consume
the YARP nodes directly. Baby steps. :-)

We don't handle the variable setting yet, but we didn't with
NatalieParser either.

I need to learn how to say something like "unexpected X, expected Y"...