code: function evalMixin(node, result) {
  		let key = node.name,
  			mixin = mixins[key];
  
  		if (! mixin) {
  			node.warn(result, 'Mixin not found.');
  			return [];
  		}
  
  		return mixin.apply(mixins, getArguments(key, mixin, node.arguments));
  	}
docs: Evaluate mixin
  
  @param {object} node - postcss.Node
  @param {object} result - postcss.Result
  @returns {array|object}