There's a typo in the code in "the substitution model" section: ("+", ("fib", ("-", "n", 2)), ("fib", ("-", "n", 1))), The two calls to `fib` are surely mea

There's a typo in the code in "the substitution model" section: ("+", ("fib", ("-", "n", 2)), ("fib", ("-", "n", 1))), The two calls to `fib` are surely meant to be `fibonacci` since the latter is defined, but not the former. Indeed, the code is correct in the github repo: https://github.com/savarin/pyscheme/blob/0f47292c8e5112425b50db19b744a50d8cabde4f/src/test_pyscheme.py#L27 https://github.com/savarin/pyscheme/blob/0f47292c8e5112425b5...