How to use the jinja2.nodes function in Jinja2

def generic_visit(self, node, *args, **kwargs):
        node = super(Optimizer, self).generic_visit(node, *args, **kwargs)

        # Do constant folding. Some other nodes besides Expr have
        # as_const, but folding them causes errors later on.
        if isinstance(node, nodes.Expr):
            try:
                return nodes.Const.from_untrusted(
                    node.as_const(args[0] if args else None),
                    lineno=node.lineno,
                    environment=self.environment,
                )
            except nodes.Impossible:
                pass

        return node

from jinja2.runtime import __all__ as exported
        self.writeline('from __future__ import division')
        self.writeline('from jinja2.runtime import ' + ', '.join(exported))
        if not unoptimize_before_dead_code:
            self.writeline('dummy = lambda *x: None')

        # if we want a deferred initialization we cannot move the
        # environment into a local name
        envenv = not self.defer_init and ', environment=environment' or ''

        # do we have an extends tag at all?  If not, we can save some
        # overhead by just not processing any inheritance code.
        have_extends = node.find(nodes.Extends) is not None

        # find all blocks
        for block in node.find_all(nodes.Block):
            if block.name in self.blocks:
                self.fail('block %r defined twice' % block.name, block.lineno)
            self.blocks[block.name] = block

        # find all imports and import them
        for import_ in node.find_all(nodes.ImportedName):
            if import_.importname not in self.import_aliases:
                imp = import_.importname
                self.import_aliases[imp] = alias = self.temporary_identifier()
                if '.' in imp:
                    module, obj = imp.rsplit('.', 1)
                    self.writeline('from %s import %s as %s' %
                                   (module, obj, alias))
                else:
                    self.writeline('import %s as %s' % (imp, alias))

@visits_expr(nodes.Name)
def visit_name(ast, ctx, macroses=None, config=default_config):
    kwargs = {
        'order_nr': config.ORDER_OBJECT.get_next()
    }
    return ctx.return_struct_cls.from_ast(ast, **kwargs), Dictionary({
        ast.name: ctx.get_predicted_struct(label=ast.name)
    })

def parse_add(self):
        lineno = self.stream.current.lineno
        left = self.parse_sub()
        while self.stream.current.type == 'add':
            next(self.stream)
            right = self.parse_sub()
            left = nodes.Add(left, right, lineno=lineno)
            lineno = self.stream.current.lineno
        return left

def parse_sub(self):
        lineno = self.stream.current.lineno
        left = self.parse_concat()
        while self.stream.current.type == 'sub':
            next(self.stream)
            right = self.parse_concat()
            left = nodes.Sub(left, right, lineno=lineno)
            lineno = self.stream.current.lineno
        return left

def parse(self, parser):
        node = nodes.ExprStmt(lineno=next(parser.stream).lineno)
        node.node = parser.parse_tuple()
        return node

self.stream.look().type == 'assign':
                    key = self.stream.current.value
                    self.stream.skip(2)
                    value = self.parse_expression()
                    kwargs.append(nodes.Keyword(key, value,
                                                lineno=value.lineno))
                else:
                    ensure(not kwargs)
                    args.append(self.parse_expression())

            require_comma = True
        self.stream.expect('rparen')

        if node is None:
            return args, kwargs, dyn_args, dyn_kwargs
        return nodes.Call(node, args, kwargs, dyn_args, dyn_kwargs,
                          lineno=token.lineno)

def free_identifier(self, lineno=None):
        """Return a new free identifier as :class:`~jinja2.nodes.InternalName`."""
        self._last_identifier += 1
        rv = object.__new__(nodes.InternalName)
        nodes.Node.__init__(rv, 'fi%d' % self._last_identifier, lineno=lineno)
        return rv

if self.environment.newstyle_gettext:
            for key, value in iteritems(variables):
                # the function adds that later anyways in case num was
                # called num, so just skip it.
                if num_called_num and key == 'num':
                    continue
                node.kwargs.append(nodes.Keyword(key, value))

        # otherwise do that here
        else:
            # mark the return value as safe if we are in an
            # environment with autoescaping turned on
            node = nodes.MarkSafeIfAutoescape(node)
            if variables:
                node = nodes.Mod(node, nodes.Dict([
                    nodes.Pair(nodes.Const(key), value)
                    for key, value in variables.items()
                ]))
        return nodes.Output([node])

def parse_unary(self, with_filter=True):
        token_type = self.stream.current.type
        lineno = self.stream.current.lineno
        if token_type == 'sub':
            next(self.stream)
            node = nodes.Neg(self.parse_unary(False), lineno=lineno)
        elif token_type == 'add':
            next(self.stream)
            node = nodes.Pos(self.parse_unary(False), lineno=lineno)
        else:
            node = self.parse_primary()
        node = self.parse_postfix(node)
        if with_filter:
            node = self.parse_filter_expr(node)
        return node