How to Use __getstate__ and __setstate__ for Pickle in Python

import pickle

class Temperature:
    def __init__(self, celsius):
        self.celsius = celsius

    def __getstate__(self):
        """Customize what gets pickled."""
        state = self.__dict__.copy()
        # Convert to Fahrenheit for storage (simulate transformation)
        state['fahrenheit'] = (self.celsius * 9 / 5) + 32
        # Remove the original attribute to reduce payload
        del state['celsius']
        return state

    def __setstate__(self, state):
        """Customize how the object is restored."""
        # Reconstruct celsius from stored fahrenheit
        self.celsius = (state['fahrenheit'] - 32) * 5 / 9
        self.__dict__.update(state)

if __name__ == "__main__":
    original = Temperature(25)
    data = pickle.dumps(original)
    restored = pickle.loads(data)
    print(f"Original celsius: {original.celsius}")
    print(f"Pickled state: {data!r}")
    print(f"Restored celsius: {restored.celsius:.2f}")
    print(f"Restored has fahrenheit: {hasattr(restored, 'fahrenheit')}")