code: def ref(self, name: str) -> str:
      rv = self.find_ref(name)
      if rv is None:
          raise AssertionError(
              "Tried to resolve a name to a reference that was"
              f" unknown to the frame ({name!r})"
          )
      return rv
  
imports: import typing
  from .None import nodes
  from .visitor import NodeVisitor
label_desc: Use image node_id 6 for calling the Symbols obj's underlying member method code with example usage: obj.ref(name) and returns: rv