def import_book(stream):
 (format, stream) = detect(stream)
 try:
  databook = Databook()
  format.import_book(databook, stream)
  return databook
 except AttributeError:
  return None

def import_book ( stream ) : ( format , stream ) = detect ( stream ) try : databook = Databook ( ) format . import_book ( databook , stream ) return databook except AttributeError : return None
return dataset of given stream .