<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def namespace(self, prefix=None):
 """ Get this schema element's target namespace. In case of reference elements, the target namespace is defined by the referenced and not the referencing element node. @param prefix: The default prefix. @type prefix: str @return: The schema element's target namespace @rtype: (I{prefix},I{URI}) """

        e = self.__deref()
        if e is not None:
            return e.namespace(prefix)
        return super(Element, self).namespace()