Generates a useful node from the data provided.

def _make_node(self, singular, plural, variables, plural_expr):
        """Generates a useful node from the data provided."""
        # singular only:
        if plural_expr is None:
            gettext = nodes.Name('gettext', 'load')
            node = nodes.Call(gettext, [nodes.Const(singular)],
                              [], None, None)

        # singular and plural
        else:
            ngettext = nodes.Name('ngettext', 'load')
            node = nodes.Call(ngettext, [
                nodes.Const(singular),
                nodes.Const(plural),
                plural_expr
            ], [], None, None)

        # mark the return value as safe if we are in an
        # environment with autoescaping turned on
        if self.environment.autoescape:
            node = nodes.MarkSafe(node)

        if variables:
            node = nodes.Mod(node, variables)
        return nodes.Output([node])