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

operate: function (op, other) {
        return new(tree.Dimension)
                  (tree.operate(op, this.value, other.value),
                  this.unit || other.unit);
    }
};

operate: function (op, other) {
        return new(tree.Dimension)
                  (tree.operate(op, this.value, other.value),
                  this.unit || other.unit);
    }
};

operate: function (op, other) {
        return new(tree.Dimension)
                  (tree.operate(op, this.value, other.value),
                  this.unit || other.unit);
    }
};

dimension: function () {
                    var value, c = input.charCodeAt(i);
                    if ((c > 57 || c < 45) || c === 47) return;

                    if (value = $(/(-?[0-9]*\.?[0-9]+)(px|%|em|pc|ex|in|deg|s|ms|pt|cm|mm)?/g)) {
                        return new(tree.Dimension)(value[1], value[2]);
                    }
                }
            },

dimension: function () {
                    var value, c = input.charCodeAt(i);
                    if ((c > 57 || c < 45) || c === 47) return;

                    if (value = $(/(-?[0-9]*\.?[0-9]+)(px|%|em|pc|ex|in|deg|s|ms|pt|cm|mm)?/g)) {
                        return new(tree.Dimension)(value[1], value[2]);
                    }
                }
            },

greyscale: function (color, amount) {
        return this.desaturate(color, new(tree.Dimension)(100));
    },
    e: function (str) {

greyscale: function (color, amount) {
        return this.desaturate(color, new(tree.Dimension)(100));
    },
    e: function (str) {

dimension: function () {
                    var value, c = input.charCodeAt(i);
                    if ((c > 57 || c < 45) || c === 47) return;

                    if (value = $(/(-?[0-9]*\.?[0-9]+)(px|%|em|pc|ex|in|deg|s|ms|pt|cm|mm)?/g)) {
                        return new(tree.Dimension)(value[1], value[2]);
                    }
                }
            },

greyscale: function (color, amount) {
        return this.desaturate(color, new(tree.Dimension)(100));
    },
    e: function (str) {