old_contents: from app import db
  from flask_login import UserMixin
  
  class User(UserMixin, db.Model):
      __tablename__ = 'users'
      id = db.Column(db.Integer, primary_key=True)
      nickname = db.Column(db.String(64), index=True, unique=True)
      name = db.Column(db.String(64), index=True)
      email = db.Column(db.String(64), index=True, unique=True)
      date = db.Column(db.DateTime)
      height = db.Column(db.Float(Precision=2))
      age = db.Column(db.Integer)
  
      @property
      def is_authenticated(self):
          return True
  
      @property
      def is_active(self):
          return True
  
      @property
      def is_anonymous(self):
          return False
  
      def __repr__(self):
          return '<User %r>' % (self.nickname)
  
      def get_id(self):
          try:
              return unicode(self.id) # python2
          except NameError:
              return str(self.id) # python3
  
      @staticmethod
      def make_unique_nickname(nickname):
          if User.query.filter_by(nickname=nickname).first() is None:
              return nickname
          version = 2
          while True:
              new_nickname = nickname + str(version)
              if User.query.filter_by(nickname=new_nickname).first() is None:
                  break
              version += 1
          return new_nickname
  
new_contents: from app import db
  from flask_login import UserMixin
  
  
  class User(UserMixin, db.Model):
      __tablename__ = 'users'
      id = db.Column(db.Integer, primary_key=True)
      nickname = db.Column(db.String(64), index=True, unique=True)
      name = db.Column(db.String(64), index=True)
      email = db.Column(db.String(64), index=True, unique=True)
      date = db.Column(db.DateTime)
      height = db.Column(db.Float(Precision=2))
      age = db.Column(db.Integer)
  
      @property
      def is_authenticated(self):
          return True
  
      @property
      def is_active(self):
          return True
  
      @property
      def is_anonymous(self):
          return False
  
      def __repr__(self):
          return '<User %r>' % (self.nickname)
  
      def get_id(self):
          try:
              return unicode(self.id)
          except NameError:
              return str(self.id)
  
      @staticmethod
      def make_unique_nickname(nickname):
          if User.query.filter_by(nickname=nickname).first() is None:
              return nickname
          version = 2
          while True:
              new_nickname = nickname + str(version)
              if User.query.filter_by(nickname=new_nickname).first() is None:
                  break
              version += 1
          return new_nickname
  
subject: Modify to fit with PEP8 standard