A usable repr for objects from the declarative_base hierarchy

Base = declarative_base()
def __Base__repr__(self):
    """A usable repr for objects from the declarative_base hierarchy"""
    atts = []
    for key in self.__table__.c.keys():
        if key in self.__dict__:
            if not (hasattr(self.__table__.c.get(key).default, 'arg') and
                    getattr(self.__table__.c.get(key).default, 'arg') == getattr(self, key)):
                atts.append( (key, getattr(self, key)) )

    return self.__class__.__name__ + '(' + ', '.join(x[0] + '=' + repr(x[1]) for x in atts) + ')'
Base.__repr__ = __Base__repr__