code: def _greyscale_check_parameters(start=None, end=None):
      # Up to v.1.4.2 start/end values were in range [0,100]
      # Since v.1.4.3 start/end values are in range [0,1]
      if start != None and not (0 <= start <= 1):
          start = start / 100
          print(
              "WARN: Value of 'start' has been scaled down to range: [0,1] : {}".format(
                  start
              )
          )
  
      if end != None and not (0 <= end <= 1):
          end = end / 100
          print(
              "WARN: Value of 'end' has been scaled down to range: [0,1] : {}".format(
                  end
              )
          )
  
      if start != None and not (0 <= start <= 1):
          raise ValueError(
              "Value of 'start' must be in range: [0,1] : {}".format(
                  start
              )
          )
  
      if end != None and not (0 <= end <= 1):
          raise ValueError(
              "Value of 'end' must be in range: [0,1] : {}".format(end)
          )
  
      return (start, end)
  
imports: from .core import FeatureSpec, FeatureSpecArray
  from .util import as_boolean
label_desc: Use image node_id 30 for calling a global function with example usage: _greyscale_check_parameters(start, end) and returns: start,  end