What is the role of metaclasses in the Python programming language and what are they used for?

Metaclasses in Python are classes that create other classes. Simply put, a metaclass defines the behavior of a class, just as a class defines the behavior of its instances.

The role of metaclasses:

• Allow control over the class creation process.
• Used for automatically modifying or adding attributes and methods to classes.
• Applied to implement design patterns, such as singleton.

Example of using a metaclass for logging class creation:

class Meta(type):
    def __new__(cls, name, bases, dct):
        print(f"Creating class {name}")
        return super().__new__(cls, name, bases, dct)

class MyClass(metaclass=Meta):
    pass

When defining MyClass, it will output: Creating class MyClass.

Thus, metaclasses provide a powerful tool for metaprogramming and extending the language's capabilities.