Update README.md

Author: josemoracard

exercises/042-understanding_classes/README.md

@@ -14,17 +14,16 @@ class Student:
         self.grade = grade
 
     def introduce(self): # This is a method
-        print(f"Hello! I am {self.name}, I am {self.age} years old, and my current grade is {self.grade}.")
+        return f"Hello! I am {self.name}, I am {self.age} years old, and my current grade is {self.grade}."
 
     def study(self, hours): # This is another method
-        print(f"{self.name} is studying for {hours} hours.")
         self.grade += hours * 0.5
-        print(f"After studying, {self.name}'s new grade is {self.grade}.")
+        return f"After studying for {hours} hours, {self.name}'s new grade is {self.grade}."
 
 student1 = Student("Ana", 20, 80)
 
-student1.introduce()
-student1.study(3)
+print(student1.introduce())
+print(student1.study(3))
 ```
 
 In this code: 
@@ -41,4 +40,4 @@ In this code:
 
 + Read about the `__init__` built-in function: https://www.w3schools.com/python/gloss_python_class_init.asp
 
-+ If you find yourself wondering about the role of the `self` keyword in Python classes, take a moment to visit the following link for a detailed explanation: [Understanding the 'self' Parameter](https://www.geeksforgeeks.org/self-in-python-class/)
++ If you find yourself wondering about the role of the `self` keyword in Python classes, take a moment to visit the following link for a detailed explanation: [Understanding the 'self' Parameter](https://www.geeksforgeeks.org/self-in-python-class/)