code: def export_left_unit16() -> None:
      node = onnx.helper.make_node(
          "BitShift", inputs=["x", "y"], outputs=["z"], direction="LEFT"
      )
  
      x = np.array([16, 4, 1]).astype(np.uint16)
      y = np.array([1, 2, 3]).astype(np.uint16)
      z = x << y  # expected output [32, 16, 8]
      expect(
          node,
          inputs=[x, y],
          outputs=[z],
          name="test_bitshift_left_uint16",
      )
  
file_path: onnx/onnx/backend/test/case/node/bitshift.py
imports: 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 6 for calling the BitShift obj's underlying member method code with example usage: obj.export_left_unit16() without return types