old_contents: from flask_wtf import Form
  from wtforms import (
      StringField, PasswordField, BooleanField, SubmitField,
      ValidationError,
  )
  from wtforms.validators import (
      InputRequired, Length, Email, Regexp, EqualTo,
  )
  
  from app.models import User
  
  
  class LoginForm(Form):
      email = StringField('Email', validators=[
          InputRequired(), Length(1, 64), Email()])
      password = PasswordField('Senha', validators=[InputRequired()])
      remember_me = BooleanField('Lembrar')
      submit = SubmitField('Log In')
  
  
  class RegistrationForm(Form):
      email = StringField('Email', validators=[
          InputRequired(), Length(1, 64), Email()])
      username = StringField('Username', validators=[
          InputRequired(), Length(1, 64)])
      password = PasswordField('Senha', validators=[
          InputRequired(), EqualTo('password2',
                                   message='Senhas devem ser iguais')])
      password2 = PasswordField('Confirmar senha', validators=[InputRequired()])
      submit = SubmitField('Registrar')
  
      def validate_email(self, field):
          if User.query.filter_by(email=field.data).first():
              raise ValidationError('Esse email já está em uso!')
  
      def validate_username(self, field):
          if User.query.filter_by(username=field.data).first():
              raise ValidationError('Esse usuário já está em uso!')
  
new_contents: from flask_wtf import FlaskForm
  from wtforms import (
      StringField, PasswordField, BooleanField, SubmitField,
      ValidationError,
  )
  from wtforms.validators import (
      InputRequired, Length, Email, Regexp, EqualTo,
  )
  
  from app.models import User
  
  
  class LoginForm(FlaskForm):
      email = StringField('Email', validators=[
          InputRequired(), Length(1, 64), Email()])
      password = PasswordField('Senha', validators=[InputRequired()])
      remember_me = BooleanField('Lembrar')
      submit = SubmitField('Log In')
  
  
  class RegistrationForm(FlaskForm):
      email = StringField('Email', validators=[
          InputRequired(), Length(1, 64), Email()])
      username = StringField('Username', validators=[
          InputRequired(), Length(1, 64)])
      password = PasswordField('Senha', validators=[
          InputRequired(), EqualTo('password2',
                                   message='Senhas devem ser iguais')])
      password2 = PasswordField('Confirmar senha', validators=[InputRequired()])
      submit = SubmitField('Registrar')
  
      def validate_email(self, field):
          if User.query.filter_by(email=field.data).first():
              raise ValidationError('Esse email já está em uso!')
  
      def validate_username(self, field):
          if User.query.filter_by(username=field.data).first():
              raise ValidationError('Esse usuário já está em uso!')
  
subject: Change Form to FlaskForm (previous is deprecated)