old_contents: import datetime
  
  import mongoengine
  from mongoengine.django import auth
  
  from piplmesh.account import fields
  
  class User(auth.User):
      birthdate = fields.LimitedDateTimeField(upper_limit=datetime.datetime.today(), lower_limit=datetime.datetime.today() - datetime.timedelta(366 * 120))
      gender = fields.GenderField()
      language = fields.LanguageField()
      
      facebook_id = mongoengine.IntField()
      facebook_token = mongoengine.StringField(max_length=150)
  
new_contents: import datetime
  
  import mongoengine
  from mongoengine.django import auth
  
  from piplmesh.account import fields
  
  class User(auth.User):
      birthdate = fields.LimitedDateTimeField(upper_limit=datetime.date.today(), lower_limit=datetime.date.today() - datetime.timedelta(366 * 120))
      gender = fields.GenderField()
      language = fields.LanguageField()
      
      facebook_id = mongoengine.IntField()
      facebook_token = mongoengine.StringField(max_length=150)
  
subject: Change date's limits format to datetime.date.