Fake multi-inheritance mixin function for TypeScript

mixin.ts

///////////
// Code //
/////////

/**
 * A little helper for TSC to understand whats going on...
 */
interface Constructor<T> {
    new (...args: any[]): T;
}

/**
 * Fake multi-inheritance mixin function - perfectly fits into pattern where one compses 
 * reusable components by combining simpler partial classes. Achieves this by leveraging 
 * mixin function (inspired by like Scala).
 * 
 * TS understand hybrid class created with this mixin, allows autocomplition & validation.
 */
function mixin<W extends Constructor<{}>, K extends Constructor<{}>>(Base: W, Additive: K, ...additiveArgs: any[]) {
    const Premix = class extends Base {
        constructor(...args: any[]) {
            super(...args);
        }
    };

    const additive = new Additive(...additiveArgs);

    Object.keys(additive).forEach(name => {
        Premix.prototype[name] = additive[name];
    });

    return Premix as W & K;
}

///////////
// Test //
/////////
class Lion {
    claws = 'sharp';

    constructor(...args: any[]) {
        this.claws = `${this.claws}, tough`;
    }
}

class Scorion {
    venom: string;

    constructor(...args: any[]) {
        this.venom = args[0];
    }
}

const Chimera = mixin(Lion, Scorion, 'toxic');
const chimera = new Chimera();
alert(`${chimera.claws} and ${chimera.venom}`);