While I was studying Compilers,I saw an example in first and follow that illustrated how to 'find the first and follow' non-terminals in a grammer.But I couldn't get how FOLLOW(E')=FOLLOW(E)={ $ ,) } even though the first and follow algorithm states it like that.I don't understand why the FOLLOW(E') contains ')'.  Does anyone know how this works?
First and Follow Algorithm in Compiler Design
compiler