code: def _run(self, x):  # type: ignore
      # Specify np.int64 for Windows x86 machines
      res = np.vstack(np.nonzero(x)).astype(np.int64)
      return (res,)
  
imports: import numpy
  from onnx.reference.op_run import OpRun
label_desc: Use image node_id 1 for calling the NonZero obj's underlying member method code with example usage: obj._run(x) and returns: res