Search for simple values in golang code with visitor and python pattern matching.

1. Parse golang source file by running asty with docker container.
2. Create visitor that searches for fmt.Println calls with first parameter as string constant.
3. Apply visitor to parsed AST and print found parameters.

With this approach you can find static patterns in AST that you can fit into single python match. If you need to search for more complicated things you can use nested visitors or nested match in conjunction with walk. This is simple way of searching that works well for most of the cases. However, for more advanced cases you code might become very complex and verbose.