How to use the jinja2.exceptions.TemplateSyntaxError function in Jinja2

def test_restricted(self):
        env = SandboxedEnvironment()
        self.assert_raises(TemplateSyntaxError, env.from_string,
                      "{% for item.attribute in seq %}...{% endfor %}")
        self.assert_raises(TemplateSyntaxError, env.from_string,
                      "{% for foo, bar.baz in seq %}...{% endfor %}")

def test_restricted():
    env = SandboxedEnvironment()
    assert_raises(TemplateSyntaxError, env.from_string,
                  "{% for item.attribute in seq %}...{% endfor %}")
    assert_raises(TemplateSyntaxError, env.from_string,
                  "{% for foo, bar.baz in seq %}...{% endfor %}")

def unescape_string(lineno, filename, s):
    r"""Unescape a string. Supported escapes:
        \a, \n, \r\, \f, \v, \\, \", \', \0

        \x00, \u0000, \U00000000, \N{...}
    """
    try:
        return _trystr(s.encode('ascii', 'backslashreplace')
                        .decode('unicode-escape'))
    except UnicodeError, e:
        msg = str(e).split(':')[-1].strip()
        raise TemplateSyntaxError(msg, lineno, filename)

continue
            elif token == 'data':
                value = self._normalize_newlines(value)
            elif token == 'keyword':
                token = value
            elif token == 'name':
                value = str(value)
            elif token == 'string':
                # try to unescape string
                try:
                    value = self._normalize_newlines(value[1:-1]) \
                        .encode('ascii', 'backslashreplace') \
                        .decode('unicode-escape')
                except Exception as e:
                    msg = str(e).split(':')[-1].strip()
                    raise TemplateSyntaxError(msg, lineno, name, filename)
            elif token == 'integer':
                value = int(value)
            elif token == 'float':
                value = float(value)
            elif token == 'operator':
                token = operators[value]
            yield Token(lineno, token, value)

# Create the Jinja environment.
        logger.debug("Creating Jinja environment with folders: %s" %
                     self.app.templates_dirs)
        from piecrust.templating.jinja.loader import PieCrustLoader
        loader = PieCrustLoader(self.app.templates_dirs)
        from piecrust.templating.jinja.environment import PieCrustEnvironment
        self.env = PieCrustEnvironment(
            self.app,
            loader=loader,
            extensions=extensions)

        # Get types we need later.
        from jinja2 import TemplateNotFound
        from jinja2.exceptions import TemplateSyntaxError
        self._jinja_syntax_error = TemplateSyntaxError
        self._jinja_not_found = TemplateNotFound

# update brace/parentheses balance
                    if tokens == 'operator':
                        if data == '{':
                            balancing_stack.append('}')
                        elif data == '(':
                            balancing_stack.append(')')
                        elif data == '[':
                            balancing_stack.append(']')
                        elif data in ('}', ')', ']'):
                            if not balancing_stack:
                                raise TemplateSyntaxError('unexpected \'%s\'' %
                                                          data, lineno, name,
                                                          filename)
                            expected_op = balancing_stack.pop()
                            if expected_op != data:
                                raise TemplateSyntaxError('unexpected \'%s\', '
                                                          'expected \'%s\'' %
                                                          (data, expected_op),
                                                          lineno, name,
                                                          filename)
                    # yield items
                    if data or tokens not in ignore_if_empty:
                        yield lineno, tokens, data
                    lineno += data.count('\n')

                # fetch new position into new variable so that we can check
                # if there is a internal parsing error which would result
                # in an infinite loop
                pos2 = m.end()

                # handle state changes
                if new_state is not None:

expression returns an undefined value.  This can be changed
        by setting `undefined_to_none` to `False`.

        >>> env.compile_expression('var')() is None
        True
        >>> env.compile_expression('var', undefined_to_none=False)()
        Undefined

        .. versionadded:: 2.1
        """
        parser = Parser(self, source, state='variable')
        exc_info = None
        try:
            expr = parser.parse_expression()
            if not parser.stream.eos:
                raise TemplateSyntaxError('chunk after expression',
                                          parser.stream.current.lineno,
                                          None, None)
            expr.set_environment(self)
        except TemplateSyntaxError:
            exc_info = sys.exc_info()
        if exc_info is not None:
            self.handle_exception(exc_info, source_hint=source)
        body = [nodes.Assign(nodes.Name('result', 'store'), expr, lineno=1)]
        template = self.from_string(nodes.Template(body, lineno=1))
        return TemplateExpression(template, undefined_to_none)

# update brace/parentheses balance
                    if tokens == 'operator':
                        if data == '{':
                            balancing_stack.append('}')
                        elif data == '(':
                            balancing_stack.append(')')
                        elif data == '[':
                            balancing_stack.append(']')
                        elif data in ('}', ')', ']'):
                            if not balancing_stack:
                                raise TemplateSyntaxError('unexpected \'%s\'' %
                                                          data, lineno, name,
                                                          filename)
                            expected_op = balancing_stack.pop()
                            if expected_op != data:
                                raise TemplateSyntaxError('unexpected \'%s\', '
                                                          'expected \'%s\'' %
                                                          (data, expected_op),
                                                          lineno, name,
                                                          filename)
                    # yield items
                    if data or tokens not in ignore_if_empty:
                        yield lineno, tokens, data
                    lineno += data.count('\n')

                # fetch new position into new variable so that we can check
                # if there is a internal parsing error which would result
                # in an infinite loop
                pos2 = m.end()

                # handle state changes
                if new_state is not None:

expression returns an undefined value.  This can be changed
        by setting `undefined_to_none` to `False`.

        >>> env.compile_expression('var')() is None
        True
        >>> env.compile_expression('var', undefined_to_none=False)()
        Undefined

        **new in Jinja 2.1**
        """
        parser = Parser(self, source, state='variable')
        exc_info = None
        try:
            expr = parser.parse_expression()
            if not parser.stream.eos:
                raise TemplateSyntaxError('chunk after expression',
                                          parser.stream.current.lineno,
                                          None, None)
        except TemplateSyntaxError:
            exc_info = sys.exc_info()
        if exc_info is not None:
            self.handle_exception(exc_info, source_hint=source)
        body = [nodes.Assign(nodes.Name('result', 'store'), expr, lineno=1)]
        template = self.from_string(nodes.Template(body, lineno=1))
        return TemplateExpression(template, undefined_to_none)

    def fail(self, msg, lineno=None, exc=TemplateSyntaxError):
        """Convenience method that raises `exc` with the message, passed
        line number or last line number as well as the current name and
        filename.
        """
        if lineno is None:
            lineno = self.stream.current.lineno
        raise exc(msg, lineno, self.name, self.filename)