code: def arg_parser_output_expr(
      arg_index: int, a: PythonArgument, *, symint: bool = True
  ) -> PythonArgParserOutputExpr:
      has_default = a.default_init is not None
      unpack_method = arg_parser_unpack_method(
          t=a.type,
          default=a.default,
          default_init=a.default_init,
          symint=symint,
      )
      default = f", {a.default_init}" if has_default else ""
      expr = f"_r.{unpack_method}({arg_index}{default})"
  
      return PythonArgParserOutputExpr(
          name=a.name,
          expr=expr,
          index=arg_index,
          argument=a,
      )
  
imports: from dataclasses import dataclass
  from typing import Dict, List, Optional, Sequence, Set, Tuple, Union
  from torchgen.api import cpp
  from torchgen.api.types import Binding, CppSignature, CppSignatureGroup
  from torchgen.gen import pythonify_default
  from torchgen.model import Argument, BaseTy, BaseType, FunctionSchema, ListType, NativeFunction, OptionalType, Return, Type, Variant
label_desc: Use image node_id 18 for calling a global function with example usage: arg_parser_output_expr(arg_index, a) and returns: PythonArgParserOutputExpr