docs: def get_or_create_project_venv():
      """
      Create a project-level virtualenv (if it does not already exist).
  
      :return: ``VirtualEnv`` object
      """
      venv_dir = get_project_venv_dir()
  
      if os.path.exists(venv_dir):
          return VirtualEnv(venv_dir)
      else:
          return create_project_venv()