input: Write a python function to create a Human class with age and name attributes, and a greet method that prints a greeting message.
  assert Human(30, "Alice").greet() == "Hi, my name is Alice and I'm 30 years old."
  assert Human(45, "Bob").greet() == "Hi, my name is Bob and I'm 45 years old."
output: class Human:
      def __init__(self, age, name):
          self.age = age
          self.name = name
  
      def greet(self):
          return f"Hi, my name is {self.name} and I'm {self.age} years old."