python - flask报TemplateSyntaxError: expected token 'as', got 'page'

Question

TemplateSyntaxError: expected token 'as', got 'page'

Traceback (most recent call last)
File "/home/super/myproject/venv/lib/python2.7/site-packages/flask/app.py", line 1836, in __call__
return self.wsgi_app(environ, start_response)
File "/home/super/myproject/venv/lib/python2.7/site-packages/flask/app.py", line 1820, in wsgi_app
response = self.make_response(self.handle_exception(e))
File "/home/super/myproject/venv/lib/python2.7/site-packages/flask/app.py", line 1403, in handle_exception
reraise(exc_type, exc_value, tb)
File "/home/super/myproject/venv/lib/python2.7/site-packages/flask/app.py", line 1817, in wsgi_app
response = self.full_dispatch_request()
......
以下是源码（都是从书上打的）
{% extends base.html %}
{% import "bootstrap/wtf.html as wtf %}
{% block title %}Flasky - Login{% endblock %}

{% block page_content %}
<p class="page-header">
    <h1>Login</h1>
</p>
<p class="col-md-4">
    {{ wtf.quick_form(form) }}
</p>
{% endblock %}

Answer 1

import 少个引号

---

怎么会看不出来呢？