class_docstr: A visitor over Type.
  
  The default behavior recursively traverses the AST.
code: def visit_type_relation(self, tr):
      for arg in tr.args:
          self.visit(arg)
  
imports: from .ty import TypeVar, IncompleteType, TensorType, FuncType, TupleType, TypeRelation, RefType, GlobalTypeVar, TypeCall
  from .adt import TypeData
label_desc: Use image node_id 6 for calling the TypeVisitor obj's underlying member method code with example usage: obj.visit_type_relation(tr) without return types