Access a Name-Mangled Private Attribute

In Python, attributes prefixed with a double underscore (e.g., __secret) are name-mangled to include the class name (e.g., _ClassName__secret). This provides a form of private attribute behavior. Your task is to implement a utility function get_private_attribute(obj, attr_name) that returns the attribute's value when given an object instance and the "logical" attribute name (without any leading underscores). The function should: - Return the value if the attribute exists as a normal attribute (attr_name). - If not found, try the single-underscore variant (_attr_name). - If still not found, search for name-mangled versions for every class in the instance's MRO (e.g., _ClassName__attr_name) and return the first one found (starting from the instance's class and going up the MRO). - If no matching attribute is found, return None. This exercise helps you understand how name-mangling works and how to robustly access attributes across encapsulation boundaries for debugging, testing, or serialization code.

Implement get_private_attribute(obj, attr_name) that returns the value of an attribute even if it's stored as a name-mangled private attribute or a single-underscore protected attribute. Return None if not found.

Do not modify the classes. The function must search: direct name, single-underscore variant, then name-mangled variants for each class in the MRO. Return None if not found.