code: def scale_zero_to_min_max(scale, zero_point):
      scale = float(scale)
      zero_point = float(zero_point)
      minval = -zero_point * scale
      maxval = (255.0 - zero_point) * scale
      return minval, maxval
  
imports: from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  import numpy
  import math
  from transform.base_converter import DeviceType
label_desc: Use image node_id 13 for calling a global function with example usage: scale_zero_to_min_max(scale, zero_point) and returns: minval,  maxval