'See L{IReactorPluggableNameResolver}.
@param resolver: See L{IReactorPluggableNameResolver}.
@return: see L{IReactorPluggableNameResolver}.'

def installNameResolver(self, resolver):

    previousNameResolver = self._nameResolver
    self._nameResolver = resolver
    self.resolver = _ComplexResolverSimplifier(resolver)
    return previousNameResolver
