I am working on a React Native project. On some tutorials I have seen to bind a method like this:

constructor(props){

super(props);

this.my_function = this.my_function.bind(this);

}

My question is if I can access the function in constructor using this.my_function then why I need to bind this again? I have Java and Python background, may be that's why I am confused with this type of method binding.
Note: I know that if I don't bind a method in React Native/React JS my method won't work correctly. I just want to know why I need this extra binding.