code: def find_identity(session, id_):
      
      identity = session.query(Identity). \
          filter(Identity.id == id_).first()
  
      return identity
docs: Find an identity.
  
      Find an identity by its ID using the given `session`.
      When the identity does not exist the function will
      return `None`.
  
      :param session: database session
      :param id_: id of the identity to find
  
      :returns: an identity object; `None` when the identity
          does not exist