code: def __str__(self) -> str:
      """Emit CUDA program like the following format.
  
      <<head>> {
        <<begin codes>>
        ...;
        <<end codes>>
      }
      """
  
      return "\n".join(self._to_str_list())
  
imports: from typing import Any, List
label_desc: Use image node_id 3 for calling the CodeBlock obj's underlying member method code with example usage: obj.__str__() and returns: str