var Person = function(name) {
   this.name = name;
};

// Part 2
Person.prototype.getName = function() {
   return this.name;
};

var thomas = new Person('Thomas');
var amy = new Person('Amy');

console.info(thomas.name) // --> "Thomas"

// Part 3

console.info(thomas.getName.call(amy)); // Amy

// Part 4

delete Person.prototype.getName;
console.info(thomas.getName); // undefined
console.info(amy.getName);   // undefined