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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def prefer_type(self, prefer, over):
 """Prefer one type over another type, all else being equivalent. With abstract base classes (Python's abc module) it is possible for a type to appear to be a subclass of another type without the supertype appearing in the subtype's MRO. As such, the supertype has no order with respect to other supertypes, and this may lead to amguity if two implementations are provided for unrelated abstract types. In such cases, it is possible to disambiguate by explictly telling the function to prefer one type over the other. Arguments: prefer: Preferred type (class). over: The type we don't like (class). Raises: ValueError: In case of logical conflicts. """

        self._write_lock.acquire()
        try:
            if self._preferred(preferred=over, over=prefer):
                raise ValueError(
                    "Type %r is already preferred over %r." % (over, prefer))
            prefs = self._prefer_table.setdefault(prefer, set())
            prefs.add(over)
        finally:
            self._write_lock.release()