code: def _hue2rgb(v1, v2, vH):
      
  
      while vH < 0: vH += 1
      while vH > 1: vH -= 1
  
      if 6 * vH < 1: return v1 + (v2 - v1) * 6 * vH
      if 2 * vH < 1: return v2
      if 3 * vH < 2: return v1 + (v2 - v1) * ((2.0 / 3) - vH) * 6
  
      return v1
docs: Private helper function (Do not call directly)
  
      :param vH: rotation around the chromatic circle (between 0..1)