def installResolver(resolver):
        """
        Set the internal resolver to use to for name lookups.

        @type resolver: An object implementing the L{IResolverSimple} interface
        @param resolver: The new resolver to use.

        @return: The previously installed resolver.
        @rtype: L{IResolverSimple}
        """

        Set the internal resolver to use to for name lookups.

        @type resolver: An object implementing the L{IResolverSimple} interface
        @param resolver: The new resolver to use.

        @return: The previously installed resolver.
        @rtype: L{IResolverSimple}
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/internet/interfaces.py