code: def read_footer(filename):
      
      with open(filename, 'rb') as file_obj:
          if not _check_header_magic_bytes(file_obj) or \
             not _check_footer_magic_bytes(file_obj):
              raise ParquetFormatException("{0} is not a valid parquet file "
                                           "(missing magic bytes)"
                                           .format(filename))
          return _read_footer(file_obj)
docs: Read the footer and return the FileMetaData for the specified filename.