code: def _is_gray_image(tens):
      tens = to_tensor(tens, override_checks=True)
      return tens.is_gray()
  
imports: import numpy
  import cv2
  import random
  import collections
  from ..coreten import Tensor, to_tensor
  from .._internal import _check_target_size
  from ..globals import INTER_AREA, INTER_CUBIC, INTER_NEAREST, INTER_LINEAR
  from ..annotations import Union, Tuple, Optional
label_desc: Use image node_id 2 for calling a global function with example usage: _is_gray_image(tens) and returns: tens