code: def compute_diff(dir_base, dir_cmp):
      
      data = {}
      data['deleted'] = list(set(dir_cmp['files']) - set(dir_base['files']))
      data['created'] = list(set(dir_base['files']) - set(dir_cmp['files']))
      data['updated'] = []
      data['deleted_dirs'] = list(set(dir_cmp['subdirs']) - set(dir_base['subdirs']))
  
      for f in set(dir_cmp['files']).intersection(set(dir_base['files'])):
          if dir_base['index'][f] != dir_cmp['index'][f]:
              data['updated'].append(f)
  
      return data
docs: Compare `dir_base' and `dir_cmp' and returns a list with
      the following keys:
       - deleted files `deleted'
       - created files `created'
       - updated files `updated'
       - deleted directories `deleted_dirs'