anchor.diff:  Returns the HSL saturation of `$color` as a number between `0%` and `100%`.
   
   See also:
  +
   * [`red()`](#red) for getting a color's red channel.
   * [`green()`](#green) for getting a color's green channel.
   * [`blue()`](#blue) for getting a color's blue channel.
  
positive.code: Returns the blue channel of `$color` as a number between 0 and 255.
  
  See also:
  * [`red()`](#red) for getting a color's red channel.
  * [`green()`](#green) for getting a color's green channel.
  * [`hue()`](#hue) for getting a color's hue.
  
negative.code: unitless. The `$alpha` argument must be unitless and between -1 and 1
  (inclusive).
  
  [unitless]: ../values/numbers#units
  
  See also:
  
  * [`scale-color()`](#scale-color) for fluidly scaling a color's properties.
  * [`adjust-color()`](#adjust-color) for adjusting a color's properties by fixed
    amounts.
  