mixins.import.less, use example?

[Orbyt]

How do i use the mixins in the mixins.import? Im trying to use the gradient mixin which is specified like this in the mixins.import.less file: #gradient { .vertical(@start-color: #555; @end-color: #333; @start-percent: 0%; @end-percent: 100%) {

Ive tried #gradient.vertical(), #gradient > .vertical() etc.

How is this mixin used?