text: from flask_wtf import FlaskForm
  from wtforms import StringField, PasswordField, BooleanField, SubmitField, TextAreaField
  from wtforms.validators import DataRequired, ValidationError, Email, EqualTo, Length
  from .models import User
  
  
  class LoginForm(FlaskForm):
      username = StringField('username', validators=[DataRequired()])
      password = PasswordField('Password', validators=[DataRequired()])
      remember_me = BooleanField('Remember Me')
      submit = SubmitField('Sign In') 
  
  class RegistrationForm(FlaskForm):
      username = StringField('Username', validators=[DataRequired()])
      email = StringField('Email', validators=[DataRequired(), Email()])
      password = PasswordField('Password', validators=[DataRequired()])
      password2 = PasswordField ('Repeat Password', validators=[DataRequired(), EqualTo('password')])
      submit = SubmitField('Register')
      
  
      def validade_username(self, username):
          user = User.query.filter_by(username=username.data).first()
          if user is not None:
              raise ValidationError('Please use a different username.')
      
      def validate_email(self, email):
          user = User.query.filter_by(email=email.data).first()
          if user is not None:
              raise ValidationError('Please use a different email address.')
  
  class EditProfileForm(FlaskForm):
      username = StringField('Username', validators=[DataRequired()])
      about_me = TextAreaField('About me', validators=[Length(min=0, max=140)])
      submit = SubmitField('Submit')
  
      def __init__(self, original_username, *args, **kwargs):
          super(EditProfileForm, self).__init__(*args, **kwargs)
          self.original_username = original_username
  
      def validate_username(self, username):
          if username.data != self.original_username:
              user = User.query.filter_by(username=self.username.data).first()
              if user is not None:
                  raise ValidationError('Please use a different username.')
  
  
  class PostForm(FlaskForm):
      post = TextAreaField('Say something', validators=[
          DataRequired(), Length(min=1, max=140)])
      submit = SubmitField('Submit')
  
      
  class EmptyForm(FlaskForm):
      submit = SubmitField('Submit')