docs: def files_size(fs0, fs1, files):
      """Gets the file size of the given files."""
      for file_meta in files['deleted_files']:
          file_meta['size'] = fs0.stat(file_meta['path'])['size']
      for file_meta in files['created_files'] + files['modified_files']:
          file_meta['size'] = fs1.stat(file_meta['path'])['size']
  
      return files