- Chapter 2 Basic application
    - the skeleton of one app - app = Flask(__name__); app.run();
    - request hooks like, app.before_request (to handle like database connection)
    - app.route('/user/<name>') decorator
    - make_response
    - redirect
    - abort
    - global variable including g, current_app, request, session
    - flask-script
- Chapter 3 Template
    - render_template('index.html', name='test')
    - Jinja2 filter, like safe, lower, upper
    - control structure {%%} if else, for a in bs
    - template macro  {% macro name %} % endmacro %
    - import macro {% import 'macros.html' as macros %} -> {{ macros.method() }}
    - include repeat code,  {% include 'common.html' %}
    - inheritate, {% extends 'base.html' %}, {{ super() }}
    - flask-bootstrap
    - flask-moment
    - error handling, app.errorhandler(404)
    - url_for(view_funciton_name, param=..., _external=True)
    - url_for('static', filename='css/style.css', _external=True)