// Class decorator
function seal(constructor: Function) {
  Object.seal(constructor);
  Object.seal(constructor.prototype);
}

// Method decorator
function setTimeout(ms = 0) { // Notice the wrapper function to get arguments, this can be done to any decorator function
  return function(target: any, propertyKey: string, descriptor: PropertyDescriptor) {
    const originalMethod = descriptor.value;
    descriptor.value = function () {
      setTimeout(() => originalMethod.apply(this, arguments), ms);
    };
    return descriptor;
  }
}

// Accessor/Property decorator
function log(target: any, key: string) {
  let value = target[key];

  Object.defineProperty(target, key, {
    get: () => {
      console.log(`Get => ${key}`);
      return value;
    },
    set: (newValue) => {
      console.log(`Set: ${key} => ${e}`);
      value = newValue;
    },
    enumerable: true,
    configurable: true
  });
}

// Example
@seal
class Person { 
  @log firstName: string;
  @log lastName: string;

  @log 
  get name() { return `${this.firstName} ${this.lastName}`};

  constructor(firstName: string, lastName: string) { 
    this.firstName = firstName;
    this.lastName = lastName;
  }

  @timeout(1000)
  whoami() {
    return this.name;
  }
}