code: def UpsertUser(self, database_link, user, options=None):
          
          if options is None:
              options = {}
  
          database_id, path = self._GetDatabaseIdWithPathForUser(database_link, user)
          return self.Upsert(user,
                             path,
                             'users',
                             database_id,
                             None,
                             options)
docs: Upserts a user.
  
          :param str database_link:
              The link to the database.
          :param dict user:
              The Azure Cosmos user to upsert.
          :param dict options:
              The request options for the request.
  
          :return:
              The upserted User.
          :rtype: dict