code: def _get_destination_folder(json_spec, folder_name=None):
      
      dest_folder = folder_name or json_spec.get('folder') or '/'
      if not dest_folder.endswith('/'):
          dest_folder = dest_folder + '/'
      return dest_folder
docs: Returns destination project in which the workflow should be created.
      It can be set in the json specification or by --destination option supplied
      with `dx build`.
      The order of precedence is:
      1. --destination, -d option,
      2. 'folder' specified in the json file.