tryEval = function (val) {
                if (val instanceof Node) {
                    return val.eval(_this.context);
                }
                return val;
            }
Creates a Less list of incremental values.
Modeled after Lodash's range function, also exists natively in PHP

@param {Dimension} [start=1]
@param {Dimension} end  - e.g. 10 or 10px - unit is added to output
@param {Dimension} [step=1]