'Produce a copy of this :class:`.TypeDecorator` instance.
This is a shallow copy and is provided to fulfill part of
the :class:`.TypeEngine` contract.  It usually does not
need to be overridden unless the user-defined :class:`.TypeDecorator`
has local state that should be deep-copied.'

def copy(self):

    instance = self.__class__.__new__(self.__class__)
    instance.__dict__.update(self.__dict__)
    return instance
