code: def grayspec(k):
      
      ll = .5
      ul = .8
      delta = (ul - ll) / k
      return [GrayScale(t) for t in np.arange(ll, ul, delta)]
docs: List of gray-scale colors in HSV space as web hex triplets.
  
      For integer argument k, returns list of `k` gray-scale colors, increasingly 
      light, linearly in the HSV color space, as web hex triplets.
  
      Technical dependency of :func:`tabular.spreadsheet.aggregate_in`.
  
      **Parameters**
  
              **k** :  positive integer
  
                      Number of gray-scale colors to return.
  
      **Returns**
  
              **glist** :  list of strings
  
                      List of `k` gray-scale colors.