def _read_tag_header(fid):
 s = fid.read((4 * 4))
 if (len(s) == 0):
  return None
 return Tag(*struct.unpack('>iIii', s))

def _read_tag_header ( fid ) : s = fid . read ( ( 4 * 4 ) ) if ( len ( s ) == 0 ) : return None return Tag ( * struct . unpack ( '>iIii' , s ) )
read only the header of a tag .