code: def combine_op_type(node: _fx.Node) -> _Optional[CombinationOpType]:
      """
      Returns type of combination op at this node -> add, mul, add-relu or concat
      """
      if is_add(node):
          return CombinationOpType.Add
      elif is_mul(node):
          return CombinationOpType.Mul
      elif is_add_relu(node):
          return CombinationOpType.AddReLU
      elif is_concat(node):
          return CombinationOpType.Concat
      return None
  
imports: import operator
  from collections import defaultdict
  from enum import Enum
  from typing import Dict
  from typing import List
  from typing import Optional
  import torch
  import torch.ao.quantization
  import torch.fx
  from torch.ao.quantization.backend_config import BackendConfig
  from torch.ao.quantization.backend_config import ObservationType
  from coremltools.optimize.torch._utils.version_utils import is_torch_2
label_desc: Use image node_id 8 for calling a global function with example usage: combine_op_type(node) and returns: None, CombinationOpType, CombinationOpType, CombinationOpType, CombinationOpType