NameError: name 'app' is not defined（关键词：flask/bug）

(venv) henry@henry-virtual-machine:~/dev/myproject/flaskr$ tree
.
├── flaskr.py
├── schema.sql
├── static
└── templates

# flaskr.py

import os
import sqlite3
from flask import Flask, request, session, g, redirect, url_for, abort, \
render_template, flash

# app = Flask(__name__)

def connect_db():
rv = sqlite3.connect(app.config['DATABASE'])
rv.row_factory = sqlite3.Row
return rv

def init_db():
with app.app_context():
db = get_db()
with app.open_resource('schema.sql', mode='r') as f:
db.cursor().executescript(f.read())
db.commit()

if __name__ == '__main__':
app.run()

Traceback (most recent call last):
File "/home/henry/dev/myproject/flaskr/flaskr.py", line 23, in <module>
app.run()
NameError: name 'app' is not defined
[Finished in 1.5s]

app = Flask(__name__)

# flaskr.py

import os
import sqlite3
from flask import Flask, request, session, g, redirect, url_for, abort, \
render_template, flash

app = Flask(__name__)

def connect_db():
rv = sqlite3.connect(app.config['DATABASE'])
rv.row_factory = sqlite3.Row
return rv

def init_db():
with app.app_context():
db = get_db()
with app.open_resource('schema.sql', mode='r') as f:
db.cursor().executescript(f.read())
db.commit()

if __name__ == '__main__':
app.run()