def __repr__wrapper(self):
    """Show all attributes."""
    return "Attributes: "+", ".join(list(self.__dict__.keys()))

def __repr__dec(func):
    """Replaces the __repr__ function of a class with __repr__wrapper"""
    def call(*args, **kwargs):
        func.__repr__ = __repr__wrapper
        result = func(*args, **kwargs)
        return result
    return call

@__repr__dec
class Container(object):
    """Empty class.
    """
    def __init__(self, *args, **kwargs):
        self.metadata = args[0]
        for k,v in kwargs.items():
            self.__dict__[k] = v

occ = Container(42, how="now")

if __name__ == "__main__":
    print(occ)
    print(occ.metadata)
    print(occ.how)