Looks like they're using tokens as input as if it's natural language. You have an AST, use it. I think the limitation is the lack of graph and tree based neural

Looks like they're using tokens as input as if it's natural language. You have an AST, use it. I think the limitation is the lack of graph and tree based neural networks, but I don't think you need a neural network to search code. You already have the AST. This could be solved with a traditional analytic approach, but it's probably a lot of hard work.