Decrease the lightning of a color

Increase the lightning of a color

Increase the saturation of a color

Decrease the saturation of a color

Change the hue of a color. The angle value must be in degrees

Increase the opacity of a color

Decrease the opacity of a color

Convert the color to a greyscale version, aka set saturation to 0

Fluidly scale saturation, lightness and alpha channel.

That means that lightening an already-light color with `scaleHsl` won’t change the lightness much, but lightening
a dark color by the same amount will change it more dramatically.


For example, the lightness of a color can be anywhere between 0 and 1.0. If `scaleHsl (0, 0.4, 0) color` is called,
the resulting color’s lightness will be 40% of the way between its original lightness and 1.0. If
`scaleHsl (0, -0.4, 0) color` is called instead, the lightness will be 40% of the way between the original
and 0.


The values of the supplied tuple scale saturation, lightness, and opacity, respectively, and have a valid range of
-1.0 to 1.0.


This function is inspired by the Sass function [scale-color](http://sass-lang.com/documentation/Sass/Script/Functions.html#scale_color-instance_method).

Fluidly scale red, green, blue, and alpha channels.

That means that reddening a already-red color with `scaleRgb` won’t change the redness much, but reddening a color
with little or no red by the same amount will change it more dramatically.


For example, the redness of a color can be anywhere between 0 and 255. If `scaleRgb (0.4, 0, 0, 0) color` is called,
the resulting color’s redness will be 40% of the way between its original redness and 255. If
`scaleRgb (-0.4, 0, 0, 0) color` is called instead, the redness will be 40% of the way between the original
and 0.


The values of the supplied tuple scale red, green, blue, and alpha channels, respectively, and have a valid range of
-1.0 to 1.0.


This function is inspired by the Sass function [scale-color](http://sass-lang.com/documentation/Sass/Script/Functions.html#scale_color-instance_method).