How to use the less/tree.Element function in less

ruleset: function () {
                var selectors = [], s, rules, match, memo = i;

                if (match = peek(/([a-z.#: _-]+)[\s\n]*\{/g)) {
                    i += match[0].length - 1;
                    selectors = [new(tree.Selector)([new(tree.Element)(null, match[1])])];
                } else {
                    while (s = $(this.selector)) {
                        selectors.push(s);
                        if (! $(',')) { break }
                    }
                    if (s) $(this.comment);
                }

                if (selectors.length > 0 && (rules = $(this.block))) {
                    return new(tree.Ruleset)(selectors, rules);
                } else {
                    // Backtrack
                    furthest = i;
                    i = memo;
                }
            },

ruleset: function () {
                var selectors = [], s, rules, match, memo = i;

                if (match = peek(/([a-z.#: _-]+)[\s\n]*\{/g)) {
                    i += match[0].length - 1;
                    selectors = [new(tree.Selector)([new(tree.Element)(null, match[1])])];
                } else {
                    while (s = $(this.selector)) {
                        selectors.push(s);
                        if (! $(',')) { break }
                    }
                    if (s) $(this.comment);
                }

                if (selectors.length > 0 && (rules = $(this.block))) {
                    return new(tree.Ruleset)(selectors, rules);
                } else {
                    // Backtrack
                    furthest = i;
                    i = memo;
                }
            },

ruleset: function () {
                var selectors = [], s, rules, match, memo = i;

                if (match = peek(/([a-z.#: _-]+)[\s\n]*\{/g)) {
                    i += match[0].length - 1;
                    selectors = [new(tree.Selector)([new(tree.Element)(null, match[1])])];
                } else {
                    while (s = $(this.selector)) {
                        selectors.push(s);
                        if (! $(',')) { break }
                    }
                    if (s) $(this.comment);
                }

                if (selectors.length > 0 && (rules = $(this.block))) {
                    return new(tree.Ruleset)(selectors, rules);
                } else {
                    // Backtrack
                    furthest = i;
                    i = memo;
                }
            },

tree.mixin.Definition = function MixinDefinition(name, params, rules) {
    this.name = name;
    this.selectors = [new(tree.Selector)([new(tree.Element)(null, name)])];
    this.params = params;
    this.arity = params.length;
    this.rules = rules;
    this._lookups = {};
    this.required = params.reduce(function (count, p) {
        if (p.name && !p.value) { return count + 1 }
        else                    { return count }
    }, 0);
};
tree.mixin.Definition.prototype = {

tree.mixin.Definition = function MixinDefinition(name, params, rules) {
    this.name = name;
    this.selectors = [new(tree.Selector)([new(tree.Element)(null, name)])];
    this.params = params;
    this.arity = params.length;
    this.rules = rules;
    this._lookups = {};
    this.required = params.reduce(function (count, p) {
        if (p.name && !p.value) { return count + 1 }
        else                    { return count }
    }, 0);
};
tree.mixin.Definition.prototype = {

tree.mixin.Definition = function MixinDefinition(name, params, rules) {
    this.name = name;
    this.selectors = [new(tree.Selector)([new(tree.Element)(null, name)])];
    this.params = params;
    this.arity = params.length;
    this.rules = rules;
    this._lookups = {};
    this.required = params.reduce(function (count, p) {
        if (p.name && !p.value) { return count + 1 }
        else                    { return count }
    }, 0);
};
tree.mixin.Definition.prototype = {

call: function () {
                    var elements = [], e, c, args, index = i;

                    while (e = $(/[#.][a-zA-Z0-9_-]+/g)) {
                        elements.push(new(tree.Element)(c, e));
                        c = $('>');
                    }
                    $('(') && (args = $(this.entities.arguments)) && $(')');

                    if (elements.length > 0 && ($(';') || peek('}'))) {
                        return new(tree.mixin.Call)(elements, args, index);
                    }
                },

element: function () {
                var e, t;

                c = $(this.combinator);
                e = $(/[.#:]?[a-zA-Z0-9_-]+/g) || $('*') || $(this.attribute) || $(/\([^)@]+\)/g);

                if (e) { return new(tree.Element)(c, e) }
            },

element: function () {
                var e, t;

                c = $(this.combinator);
                e = $(/[.#:]?[a-zA-Z0-9_-]+/g) || $('*') || $(this.attribute) || $(/\([^)@]+\)/g);

                if (e) { return new(tree.Element)(c, e) }
            },

call: function () {
                    var elements = [], e, c, args, index = i;

                    while (e = $(/[#.][a-zA-Z0-9_-]+/g)) {
                        elements.push(new(tree.Element)(c, e));
                        c = $('>');
                    }
                    $('(') && (args = $(this.entities.arguments)) && $(')');

                    if (elements.length > 0 && ($(';') || peek('}'))) {
                        return new(tree.mixin.Call)(elements, args, index);
                    }
                },