'Retrieve the L{IRecord} implementation for the given record type.
@param type: A record type, such as C{A} or L{NS}.
@type type: L{int}
@return: An object which implements L{IRecord} or L{None} if none
can be found for the given type.
@rtype: L{types.ClassType}'

def lookupRecordType(self, type):

    return self._recordTypes.get(type, UnknownRecord)
