code: def ref_grad_quantize_linear(
      x, scale, zero_point, dy, round_mode, narrow_range, dtype, **kw
  ):
      dx = dy / scale
      return dx.flatten()
  
file_path: nnabla/python/test/function/test_quantize_linear.py
imports: import pytest
  import numpy
  import nnabla.functions
  from nbla_test_utils import list_context
label_desc: Use image node_id 3 for calling a global function with example usage: ref_grad_quantize_linear(x, scale, zero_point, dy, round_mode, narrow_range, dtype) and returns: dx