text: class Person:
      def __init__(self, name, age):
          self.name = name
          self.age = age
  
      @property
      def age(self):
          return self._age
  
      @age.setter
      def age(self, new_age):
          if new_age <= 0:
              raise ValueError('age has to be positive')
          self._age = new_age
  
  
  p = Person('John', 30)
  print(p.age)
  p.age = -1 # Raises ValueError.
  