How are abstract methods created in Python?

Abstract methods in Python are created using the @abstractmethod decorator, which is part of the abc module that supports defining Abstract Base Classes (ABCs). An abstract method is a method that is declared but contains no implementation. This means that any subclass that inherits from the abstract class is required to provide an implementation for that method, ensuring a certain contract in the class hierarchy.

When a class contains one or more abstract methods, it cannot be instantiated directly. Instead, it serves as a blueprint for other classes, enforcing that derived classes implement the specified abstract methods. This promotes a design principle known as Liskov Substitution, where subclasses can be easily substituted for their parent classes.

The other approaches mentioned do not effectively create abstract methods. A standard function definition provides a complete method implementation, while simply creating a class without methods does not define any abstract behavior. Lastly, while interface definitions can hint at the concept of abstract methods, they are not used directly in Python in the same way as in languages like Java or C#. Thus, using the @abstractmethod decorator is the correct and standardized way to define abstract methods in Python.