(Program
  (Module
    (Identifier))
  (Function
    (Identifier)
    (Args)
    (Other "type_declaration"
      (TypeDecl
        (Identifier)
        (StructTy
          (FieldDecl
            (Other "identifier_list"
            { (Identifier)
            ->(Identifier) }
            {-(Identifier)-})
            (Identifier)))))))