pl/sql新手求教，函数创建出错，pls-00103

SQL code

create or replace function f_bookstatue (f_bno in number) return char(4)  is

  f_statue char(4) ;
begin
  select statue into f_statue from books where bno=f_bno;
  return(f_statue);
end ;

FUNCTION F_BOOKSTATUE 编译错误

错误：PLS-00103: 出现符号 "("在需要下列之一时：
  ; is authid as cluster order
  using external varying character large deterministic
  parallel_enable pipelined aggregate result_cache
行：1
文本：create or replace function f_bookstatue (f_bno in number) return char(4) is

刚接触pl/sql，尝试为表添加一些函数，对于此类错误应该如何解决？求教。

------解决方案--------------------
return char(4) is
这里改成return char is