code: def exist_username(app, exist_role):
      username = "test_edit_user_user"
      app.appbuilder.sm.add_user(
          username,
          "first_name",
          "last_name",
          "email@email.com",
          exist_role,
          password="password",
      )
      yield username
      if app.appbuilder.sm.find_user(username):
          app.appbuilder.sm.del_register_user(username)
  
imports: from __future__ import annotations
  import datetime
  import json
  import pytest
  from airflow.jobs.job import Job
  from airflow.jobs.scheduler_job_runner import SchedulerJobRunner
  from airflow.utils import timezone
  from airflow.utils.session import create_session
  from airflow.www import app
  from tests.test_utils.asserts import assert_queries_count
  from tests.test_utils.config import conf_vars
  from tests.test_utils.www import check_content_in_response, check_content_not_in_response
label_desc: Use image node_id 31 for calling a global function with example usage: exist_username(app, exist_role) without return types