>     = note: for more information, visit https://doc.rust-lang.org/book/ch18-02-refutability.html
       >     = note: the matched value is of type `Result<ModModule<SourceRange>, Infallible>`
       > help: you might want to use `let else` to handle the variant that isn't matched
       >     |
       > 450 |         let Ok(py_program) = locator.fold(py_program) else { todo!() };
       >     |                                                       ++++++++++++++++
       >
       > For more information about this error, try `rustc --explain E0005`.
       > error: could not compile `py2erg` (lib) due to 1 previous error
       For full logs, run 'nix log /nix/store/nnqqys9422k0vhdr9jjx4z0dkx5icbcj-pylyzer-0.0.68.drv'.