Use ES6 arrow functions for cleaner code

<img width="525" alt="Screen Shot 2021-01-12 at 10 30 42" src="https://user-images.githubusercontent.com/21221412/104277938-3b956580-54c1-11eb-878d-d9eda54b75e3.png">

If we use arrow functions we won't need such kind of serial `bind` functions.