How I can add a new string to script?

I’m trying to make a plugin but it is giving error:

I’m trying to change script with script source like this:

Script.Source = Script.Source + "example = 5 \ 
print(example) "

and it is giving this error:

attempt to perform arithmetic (add) on string

also, I tried tostring to solve issue but it is giving same error again:

Script.Source = tostring(Script.Source) + "example = 5 \ 
print(example) "

How I can fix this?

Oh, I just forgot that. I confused lua with python about combining strings