input: Write a python function to create a Student object and return its full name.
  assert get_fullname(Student("John", "Doe", 20)) == "John Doe"
  assert get_fullname(Student("Jane", "Smith", 22)) == "Jane Smith"
  assert get_fullname(Student("Alice", "Johnson", 19)) == "Alice Johnson"
output: class Student:
      def __init__(self, first_name, last_name, age):
          self.first_name = first_name
          self.last_name = last_name
          self.age = age
  
  def get_fullname(student):
      return f"{student.first_name} {student.last_name}"