How to use the jinja2.nodes.Const function in Jinja2

elif token.value in ('none', 'None'):
                node = nodes.Const(None, lineno=token.lineno)
            else:
                node = nodes.Name(token.value, 'load', lineno=token.lineno)
            next(self.stream)
        elif token.type == 'string':
            next(self.stream)
            buf = [token.value]
            lineno = token.lineno
            while self.stream.current.type == 'string':
                buf.append(self.stream.current.value)
                next(self.stream)
            node = nodes.Const(''.join(buf), lineno=lineno)
        elif token.type in ('integer', 'float'):
            next(self.stream)
            node = nodes.Const(token.value, lineno=token.lineno)
        elif token.type == 'lparen':
            next(self.stream)
            node = self.parse_tuple(explicit_parentheses=True)
            self.stream.expect('rparen')
        elif token.type == 'lbracket':
            node = self.parse_list()
        elif token.type == 'lbrace':
            node = self.parse_dict()
        else:
            self.fail("unexpected '%s'" % describe_token(token), token.lineno)
        return node

def parse_kwargs(parser):
    """
    Parses keyword arguments in tags.
    """
    name = parser.stream.expect('name').value
    parser.stream.expect('assign')
    if parser.stream.current.test('string'):
        value = parser.parse_expression()
    else:
        value = nodes.Const(next(parser.stream).value)
    return (name, value)

lineno = next(parser.stream).lineno
        lex = nodes.Const(None)
        filename = nodes.Const(None)

        if not parser.stream.current.test('block_end'):
            if parser.stream.look().test('assign'):
                name = value = value1 = None
                (name, value) = parse_kwargs(parser)
                if parser.stream.skip_if('comma'):
                    (_, value1) = parse_kwargs(parser)

                (lex, filename) = (value, value1) \
                    if name == 'lex' \
                    else (value1, value)
            else:
                lex = nodes.Const(next(parser.stream).value)
                if parser.stream.skip_if('comma'):
                    filename = parser.parse_expression()

        body = parser.parse_statements(['name:endsyntax'], drop_needle=True)
        return nodes.CallBlock(
            self.call_method('_render_syntax',
                             args=[lex, filename]),
            [], [], body).set_lineno(lineno)

singular = singular.replace('%%', '%')
            if plural:
                plural = plural.replace('%%', '%')

        # 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)

        # in case newstyle gettext is used, the method is powerful
        # enough to handle the variable expansion and autoescape
        # handling itself
        if self.environment.newstyle_gettext:
            for key, value in variables.iteritems():
                # 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:

elif token.value in ('none', 'None'):
                node = nodes.Const(None, lineno=token.lineno)
            else:
                node = nodes.Name(token.value, 'load', lineno=token.lineno)
            next(self.stream)
        elif token.type == 'string':
            next(self.stream)
            buf = [token.value]
            lineno = token.lineno
            while self.stream.current.type == 'string':
                buf.append(self.stream.current.value)
                next(self.stream)
            node = nodes.Const(''.join(buf), lineno=lineno)
        elif token.type in ('integer', 'float'):
            next(self.stream)
            node = nodes.Const(token.value, lineno=token.lineno)
        elif token.type == 'lparen':
            next(self.stream)
            node = self.parse_tuple(explicit_parentheses=True)
            self.stream.expect('rparen')
        elif token.type == 'lbracket':
            node = self.parse_list()
        elif token.type == 'lbrace':
            node = self.parse_dict()
        else:
            self.fail("unexpected '%s'" % describe_token(token), token.lineno)
        return node

if token.value in ('true', 'false', 'True', 'False'):
                node = nodes.Const(token.value in ('true', 'True'),
                                   lineno=token.lineno)
            elif token.value in ('none', 'None'):
                node = nodes.Const(None, lineno=token.lineno)
            else:
                node = nodes.Name(token.value, 'load', lineno=token.lineno)
            next(self.stream)
        elif token.type == 'string':
            next(self.stream)
            buf = [token.value]
            lineno = token.lineno
            while self.stream.current.type == 'string':
                buf.append(self.stream.current.value)
                next(self.stream)
            node = nodes.Const(''.join(buf), lineno=lineno)
        elif token.type in ('integer', 'float'):
            next(self.stream)
            node = nodes.Const(token.value, lineno=token.lineno)
        elif token.type == 'lparen':
            next(self.stream)
            node = self.parse_tuple(explicit_parentheses=True)
            self.stream.expect('rparen')
        elif token.type == 'lbracket':
            node = self.parse_list()
        elif token.type == 'lbrace':
            node = self.parse_dict()
        else:
            self.fail("unexpected '%s'" % describe_token(token), token.lineno)
        if with_postfix:
            node = self.parse_postfix(node)
        return node

def parse_primary(self):
        token = self.stream.current
        if token.type == 'name':
            if token.value in ('true', 'false', 'True', 'False'):
                node = nodes.Const(token.value in ('true', 'True'),
                                   lineno=token.lineno)
            elif token.value in ('none', 'None'):
                node = nodes.Const(None, lineno=token.lineno)
            else:
                node = nodes.Name(token.value, 'load', lineno=token.lineno)
            next(self.stream)
        elif token.type == 'string':
            next(self.stream)
            buf = [token.value]
            lineno = token.lineno
            while self.stream.current.type == 'string':
                buf.append(self.stream.current.value)
                next(self.stream)
            node = nodes.Const(''.join(buf), lineno=lineno)
        elif token.type in ('integer', 'float'):
            next(self.stream)

def parse_primary(self):
        token = self.stream.current
        if token.type == 'name':
            if token.value in ('true', 'false', 'True', 'False'):
                node = nodes.Const(token.value in ('true', 'True'),
                                   lineno=token.lineno)
            elif token.value in ('none', 'None'):
                node = nodes.Const(None, lineno=token.lineno)
            else:
                node = nodes.Name(token.value, 'load', lineno=token.lineno)
            next(self.stream)
        elif token.type == 'string':
            next(self.stream)
            buf = [token.value]
            lineno = token.lineno
            while self.stream.current.type == 'string':
                buf.append(self.stream.current.value)
                next(self.stream)
            node = nodes.Const(''.join(buf), lineno=lineno)
        elif token.type in ('integer', 'float'):
            next(self.stream)
            node = nodes.Const(token.value, lineno=token.lineno)
        elif token.type == 'lparen':
            next(self.stream)

elif token.value in ('none', 'None'):
                node = nodes.Const(None, lineno=token.lineno)
            else:
                node = nodes.Name(token.value, 'load', lineno=token.lineno)
            next(self.stream)
        elif token.type == 'string':
            next(self.stream)
            buf = [token.value]
            lineno = token.lineno
            while self.stream.current.type == 'string':
                buf.append(self.stream.current.value)
                next(self.stream)
            node = nodes.Const(''.join(buf), lineno=lineno)
        elif token.type in ('integer', 'float'):
            next(self.stream)
            node = nodes.Const(token.value, lineno=token.lineno)
        elif token.type == 'lparen':
            next(self.stream)
            node = self.parse_tuple(explicit_parentheses=True)
            self.stream.expect('rparen')
        elif token.type == 'lbracket':
            node = self.parse_list()
        elif token.type == 'lbrace':
            node = self.parse_dict()
        else:
            self.fail("unexpected '%s'" % describe_token(token), token.lineno)
        if with_postfix:
            node = self.parse_postfix(node)
        return node