code: def __add__(self, other):
      assert isinstance(other, str)
      return str(self.val + other.val)
  
imports: from .annotate import annotate, class_annotate, delay_type
  from .type_spec import Type
label_desc: Use image node_id 3 for calling the str obj's underlying member method code with example usage: obj.__add__(other) and returns: str