code: def complementary(clr):
      
      clr = color(clr)
      colors = colorlist(clr)
  
      # A contrasting color: much darker or lighter than the original.
      c = clr.copy()
      if clr.brightness > 0.4:
          c.brightness = 0.1 + c.brightness * 0.25
      else:
          c.brightness = 1.0 - c.brightness * 0.25
      colors.append(c)
  
      # A soft supporting color: lighter and less saturated.
      c = clr.copy()
      c.brightness = 0.3 + c.brightness
      c.saturation = 0.1 + c.saturation * 0.3
      colors.append(c)
  
      # A contrasting complement: very dark or very light.
      clr = clr.complement
      c = clr.copy()
      if clr.brightness > 0.3:
          c.brightness = 0.1 + clr.brightness * 0.25
      else:
          c.brightness = 1.0 - c.brightness * 0.25
      colors.append(c)
  
      # The complement and a light supporting variant.
      colors.append(clr)
  
      c = clr.copy()
      c.brightness = 0.3 + c.brightness
      c.saturation = 0.1 + c.saturation * 0.25
      colors.append(c)
  
      return colors
docs: Returns a list of complementary colors.
  
      The complement is the color 180 degrees across
      the artistic RYB color wheel.
      The list contains darker and softer contrasting
      and complementing colors.