class_docstr: `ConcreteProxy` is a wrapped proxy carried the real intermediate value.
  We can use it to trace a more compatible model, and pass the branches.
class_docstr_tok: ["`","ConcreteProxy","`","is","a","wrapped","proxy","carried","the","real","intermediate","value",".","We","can","use","it","to","trace","a","more","compatible","model",",","and","pass","the","branches","."]
code: def __iter__(self) -> Union[Iterable, ConcreteProxy]:
      # to detect if in executing `*proxy`, or `a, b, c = atuple`
      frame = inspect.currentframe()
      assert frame is not None
      calling_frame = frame.f_back
      assert calling_frame is not None
      cur = calling_frame.f_lasti // 2
      insts: List[dis.Instruction] = _orig_list(
          dis.get_instructions(calling_frame.f_code)
      )
      while insts[cur].opcode == self.op_extended_arg:
          cur += 1
  
      if insts[cur].opcode == self.op_call_ex:
          # in executing func(..., *proxy)
          # todo: don't know the func has type_guard or not
          return ConcreteUnpackIterProxy(self)
      elif insts[cur].opcode == self.op_tuple_unpack_call:
          # in executing func(*..., *proxy)
          # todo: don't know the func has type_guard or not
          # <= python 3.8
          return ConcreteUnpackIterProxy(self)
      elif insts[cur].opcode == self.op_list_extend:
          # in executing x.extend(proxy) or [x, *proxy]
          # >= python 3.9
          return ConcreteUnpackIterProxy(self)
      elif insts[cur].opcode == self.op_unpack_sequence:
          # in executing `a, b, c = atuple`
          return ConcreteUnpackIterProxy(self)
      elif (
          insts[cur].opname == "GET_ITER"
          and insts[cur + 1].opname == "FOR_ITER"
          and _orig_isinstance(self.value, _orig_range)
      ):
          # in executing `for i in range(...)`
          return iter(self.value)
      # elif insts[cur].opname == 'CONTAINS_OP':
      #     # in executing `for i in range(...)`
      #     return iter(self.value)
      else:
          return self.tracer.create_proxy(
              "call_function", iter, (self,), {}
          )
  
imports: from __future__ import annotations
  import dis
  import logging
  import inspect
  import operator
  from typing import List, Optional, Iterable, Any, Set, Union
  import torch
  from torch.fx._compatibility import compatibility
  from torch.fx.graph import magic_methods, reflectable_magic_methods
  from torch.fx.node import Node
  from torch.fx.proxy import Proxy
  from torch.overrides import is_tensor_method_or_property
  from .None import concrete_tracer
  from .utils import _orig_tuple, _orig_list, _orig_type, _orig_isinstance, _orig_getattr, _orig_range, _orig_dict, _orig_len, _orig_index, _orig_bool, _orig_slice, _orig_set, map_recursive
label_desc: Use image node_id 5 for calling the ConcreteProxy obj's underlying member method code with example usage: obj.__iter__() and returns: ConcreteUnpackIterProxy, ConcreteUnpackIterProxy, ConcreteUnpackIterProxy, ConcreteUnpackIterProxy, iter, self