Thank you! Looks good! I left a couple of small comments inline - but there is a bigger question about the general approach.

Specifically, we used to have these implementations but we removed them some time ago because we needed to specify serialization options for ProgramAst and ModuleAst, and unfortunately, Winterfell serialization traits do not provide a way to specify such options.

So, we have a couple of things to consider:

1. If we want to provide Serializable and Deserializable implementations, what serialization options should we use as the default? (one approach is to serialize everything, which is what the current implementation is doing).
2. Another option could be to add write_into() and read_from() methods to the struct. These methods would have similar signatures to what is in the traits, but would also take an additional AstSerdeOptions as a parameter.
   a. With this approach we may also be able get rid of write_source_locations and load_source_locations methods as these could be just another option in AstSerdeOptions.
3. We could also combine the above approaches - e.g., implement concrete methods and then call them from trait implementations passing default AstSerdeOptions as parameters.
4. Lastly, we could try to modify Winterfell to add an associated type for serialization/deserialization options - but without default associated types this would be a breaking change, and may not be worth it for now.