Can you explain the principle of the Singleton pattern and where it is usually used?

The Singleton pattern guarantees that a class has only one instance and provides a global point of access to it.

This is useful when you need to control access to a resource, such as a database, logger, or configuration.

Example of implementing Singleton in Python:

class Singleton:
    _instance = None

    def __new__(cls, *args, **kwargs):
        if not cls._instance:
            cls._instance = super().__new__(cls)
        return cls._instance

# Usage
s1 = Singleton()
s2 = Singleton()
print(s1 is s2)  # True

Singletons are typically used for objects that should be unique within an application to avoid conflicts and resource overuse.