code: def _get_mapping():
      
      global _STATIC_MAPPING
  
      if _STATIC_MAPPING is None:
          manifest_path = getattr(settings,
              'DJANGO_GULP_REV_PATH',
              os.path.join(getattr(settings, 'STATIC_ROOT', ''), 'rev-manifest.json'))
          
          try:
              with open(manifest_path) as manifest_file:
                  _STATIC_MAPPING = json.load(manifest_file)
          except IOError:
              return None
  
      return _STATIC_MAPPING
docs: Finds and loads gulp's rev-manifest.json file.
      In default, this is looking for rev-manifest.json file places in your
      STATIC_ROOT. Can be overriden to a specific location by setting
      DJANGO_GULP_REV_PATH.