我的代码如下，希望能够帮我解答一下，谢谢

-- coding: UTF-8 --

import os
from flask import Flask, render_template, session, redirect, url_for, flash
from flask_sqlalchemy import SQLAlchemy
from flask_bootstrap import Bootstrap
from flask_moment import Moment
from datetime import datetime

加入一个datetime变量

from flask_wtf import Form
from wtforms import StringField, SubmitField
from wtforms.validators import Required

调用表单模块

from flask_mail import Mail

配置并使用邮箱

from flask_mail import Message

集成电子邮件功能

app = Flask(__name__)

mail = Mail(app)
app.config['MAIL_SERVER'] = 'smtp.163.com'
app.config['MAIL_PORT'] = 25
app.config['MAIL_USE_TLS'] = True
app.config['MAIL_USERNAME'] = os.environ.get('MAIL_USERNAME')
app.config['MAIL_PASSWORD'] = os.environ.get('MAIL_PASSWORD')

app.config['FLASKY_MAIL_SUBJECT_PREFIX'] = '[Flasky]'app.config['FLASKY_MAIL_SENDER'] = 'Flasky Admin <17770147931@163.com>'

def send_email(to, subject, template, **kwargs):

msg = Message(app.config['FLASKY_MAIL_SUBJECT_PREFIX'] + subject,
              sender=app.config['FLASKY_MAIL_SENDER'], recipients=[to])
msg.body = render_template(template + '.txt', **kwargs)
msg.html = render_template(template + '.html', **kwargs)
mail.send(msg)

basedir = os.path.abspath(os.path.dirname(__file__))app.config['SQLALCHEMY_DATABASE_URI'] =\

'sqlite:///' + os.path.join(basedir, 'data.sqlite')

app.config['SQLALCHEMY_COMMIT_ON_TEARDOWN'] = True
app.config['SQLALCHEMY_TRACK_MODIFICATIONS'] = True
db = SQLAlchemy(app)
app.config['SECRET_KEY'] = 'hard to guess string'
bootstrap = Bootstrap(app)
moment = Moment(app)

class NameForm(Form):

name = StringField(u'在下方告诉我你的名字吧。', validators=[Required()])
submit = SubmitField(u'提交')

class Role(db.Model):

__tablename__ = 'roles'
id = db.Column(db.Integer, primary_key=True)
name = db.Column(db.String(64), unique=True)
users = db.relationship('User', backref='role', lazy='dynamic')
def __repr__(self):
    return '<Role %r>' % self.name

class User(db.Model):

__tablename__ = 'users'
id = db.Column(db.Integer, primary_key=True)
username = db.Column(db.String(64), unique=True, index=True)
role_id = db.Column(db.Integer, db.ForeignKey('roles.id'))
def __repr__(self):
    return '<User %r>' % self.username

@app.route('/', methods=['GET', 'POST'])def index():

form = NameForm()
if form.validate_on_submit():
    user = User.query.filter_by(username=form.name.data).first()
    if user is None:
        user = User(username = form.name.data)
        db.session.add(user)
        session['known'] = False
    else:
        session['known'] = True
    session['name'] = form.name.data
    form.name.data = ''
    return redirect(url_for('index'))
return render_template('index.html',
    form = form, name = session.get('name'),
    known = session.get('known', False))

@app.route('/user/<name>')

def user(name):

return render_template('user.html',name=name)

@app.errorhandler(404)def page_not_found(e):

return render_template('404.html'), 404

if name == '__main__':

app.run()