public static Book book(String name){
  if (name.equals(DEFAULT_DB_NAME))   throw new PaperDbException(DEFAULT_DB_NAME + " name is reserved for default library name");
  return getBook(name);
}

public static Book book ( String name ) { if ( name . equals ( DEFAULT_DB_NAME ) ) throw new PaperDbException ( DEFAULT_DB_NAME + " name is reserved for default library name" ) ; return getBook ( name ) ; }
returns paper book instance with the given name
