我正在尝试遵循需要使用WTForms的Flask Mega教程。正如教程中所建议的，我使用了一个虚拟环境，其中我安装了WTForms，如下所示：
flask/bin/pip install flask-wtf
这似乎工作正常，当我现在再次运行它时，我只是得到这个：
Requirement already satisfied (use --upgrade to upgrade): flask-wtf in ./flask/lib/python2.7/site-packages
Requirement already satisfied (use --upgrade to upgrade): Flask in ./flask/lib/python2.7/site-packages (from flask-wtf)
Requirement already satisfied (use --upgrade to upgrade): WTForms>=1.0 in ./flask/lib/python2.7/site-packages (from flask-wtf)
Requirement already satisfied (use --upgrade to upgrade): Werkzeug>=0.7 in ./flask/lib/python2.7/site-packages (from Flask->flask-wtf)
Requirement already satisfied (use --upgrade to upgrade): Jinja2>=2.4 in ./flask/lib/python2.7/site-packages (from Flask->flask-wtf)
Requirement already satisfied (use --upgrade to upgrade): itsdangerous>=0.21 in ./flask/lib/python2.7/site-packages (from Flask->flask-wtf)
Requirement already satisfied (use --upgrade to upgrade): markupsafe in ./flask/lib/python2.7/site-packages (from Jinja2>=2.4->Flask->flask-wtf)
Cleaning up...
但是当我尝试使用from forms import LoginForm导入表单时，出现错误说：ImportError: cannot import name LoginForm.
有谁知道我在这里做错了什么，以及我该如何解决这个问题？欢迎所有提示！
你需要一个名为 forms 的模块，其中包含 LoginForm ，
from flask.ext.wtf import Form
from wtforms import TextField, BooleanField
from wtforms.validators import Required
class LoginForm(Form):
openid = TextField('openid', validators = [Required()])
remember_me = BooleanField('remember_me', default = False)
这是取自第三部分的例子。