code: def mock_check_user():
      def _mock(user_name):
          user = Mock(spec=User)
          user.username = user_name
          user.id = f"{user_name}_id"
          return user
  
      return _mock
  
file_path: argilla/tests/unit/client/feedback/utils/test_assignment.py
imports: import warnings
  from unittest.mock import Mock, patch
  import pytest
  from argilla.client.feedback.utils.assignment import assign_records, assign_records_to_groups, assign_records_to_individuals, assign_workspaces, check_user, check_workspace
  from argilla.client.users import User
  from argilla.client.workspaces import Workspace
label_desc: Use image node_id 3 for calling a global function with example usage: mock_check_user() and returns: _mock, user