Return a list of possible refactoring options.

        This list will be filtered depending on whether it's
        applicable at the point START and possibly the region between
        START and END.

def rpc_get_refactor_options(self, filename, start, end=None):
        """Return a list of possible refactoring options.

        This list will be filtered depending on whether it's
        applicable at the point START and possibly the region between
        START and END.

        """
        try:
            from elpy import refactor
        except:
            raise ImportError("Rope not installed, refactorings unavailable")
        ref = refactor.Refactor(self.project_root, filename)
        return ref.get_refactor_options(start, end)