code: def _concat(*args, axis=0):  # type: ignore
      return np.concatenate(args, axis=axis)
  
file_path: onnx/onnx/reference/ops/op_stft.py
imports: import numpy
  from onnx.reference.op_run import OpRun
  from onnx.reference.ops.op_concat_from_sequence import _concat_from_sequence
  from onnx.reference.ops.op_dft import _cfft
  from onnx.reference.ops.op_slice import _slice
label_desc: Use image node_id 1 for calling a global function with example usage: _concat() and returns: np