code: def run_matmul_ref(a, b):
      return torch.matmul(a, b)
  
file_path: deepspeed/tests/unit/ops/transformer/inference/test_matmul.py
imports: import pytest
  import torch
  import deepspeed
  from deepspeed.ops.op_builder import InferenceBuilder
label_desc: Use image node_id 2 for calling a global function with example usage: run_matmul_ref(a, b) and returns: torch