old_contents: 
  class Account(object):
      '''Represents Account entity.
  
      This class holds user-specific information and is used
      for authorization.
  
      :param str id: account id
      :param dict details: additional details of an account
      '''
  
      def __init__(
              self, id, username, permissions, is_admin=False, **details):
          self.id = id
          self.username = username
          self.permissions = permissions
          self.is_admin = is_admin
          self.details = details
  
      def can_read(self, collection_name):
          return (
              self.is_admin or
              self.permissions.get(collection_name) in ('read', 'modify'))
  
      def can_modify(self, collection_name):
          return (
              self.is_admin or
              self.permissions.get(collection_name) == 'modify')
  
new_contents: 
  class Account(object):
      '''Represents Account entity.
  
      This class holds user-specific information and is used
      for authorization.
  
      :param str id: account id
      :param dict details: additional details of an account
      '''
  
      def __init__(
              self, id, username, permissions, is_admin=False, **details):
          self.id = id
          self.username = username
          self.permissions = permissions
          self.is_admin = is_admin
          self.details = details
  
      def can_read(self, collection_name):
          return (
              self.is_admin or
              self.permissions.get(collection_name) in ('read', 'modify'))
  
      def can_modify(self, collection_name):
          return (
              self.is_admin or
              self.permissions.get(collection_name) == 'modify')
  
      def __repr__(self):
          return (
              'Account(username={}, is_admin={})'
              .format(self.username, self.is_admin))
  
subject: add repr for Account to simply debug