code: def f(self, x: np.ndarray) -> np.ndarray:
      return 1 / (1 + np.exp(-x))
  
file_path: onnx/onnx/backend/test/case/node/lstm.py
imports: from typing import Any, Tuple
  import numpy
  import onnx
  from onnx.backend.test.case.base import Base
  from onnx.backend.test.case.node import expect
label_desc: Use image node_id 2 for calling the LSTMHelper obj's underlying member method code with example usage: obj.f(x) and returns: unknown