code: def signature_str_pyi_vararg(
      self, *, skip_outputs: bool = False
  ) -> Optional[str]:
      # only pyi uses vararg signatures
      args = self.arguments(skip_outputs=skip_outputs)
      schema_formals: List[str] = [
          a.argument_str_pyi(method=self.method) for a in args
      ]
      # vararg only applies to pyi signatures. vararg variants are not generated for all signatures
      num_args = self.arguments_count()
      num_positionalargs = len(self.input_args)
  
      have_vararg_version = False
      if num_args > 0:
          vararg_type = args[0].type
          if (
              isinstance(vararg_type, ListType)
              and str(vararg_type.elem) in ["int", "SymInt"]
              and num_positionalargs == 1
          ):
              have_vararg_version = True
  
      if not have_vararg_version:
          return None
      # Below are the major changes in vararg vs. regular pyi signatures
      # vararg signatures also omit the asterix
      schema_formals[0] = "*" + args[0].name + ": _int"
  
      returns_str = returns_str_pyi(self)
      # pyi also includes self (with no typing/defaults) for methods
      if self.method:
          schema_formals.insert(0, "self")
      return f'def {self.name}({", ".join(schema_formals)}) -> {returns_str}: ...'
  
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 7 for calling the PythonSignature obj's underlying member method code with example usage: obj.signature_str_pyi_vararg() and returns: str, self, str, str, str, returns_str, str, None