Python Singleton

I needed a singleton database class in a Python 2.7 program and wrote it this way.

class Singleton(type):
    _instances = {}
    def __call__(cls, *args, **kwargs):
        if cls not in cls._instances:
            cls._instances[cls] = super(Singleton, cls).__call__(*args, **kwargs)
        return cls._instances[cls]

class Database():
    __metaclass__ = Singleton
    def __init__(self):
        self.db = MySQLdb.connect(...)

I like this pattern but I realized that this is even more elegant:

class Database():
    db = MySQLdb.connect(...)

    def __init__(self):
        pass

It works because I do not really need the whole Database class to be a singleton. All I really want is a single database connection.