so, means it's not possible to exclude the items already with prefix. better to leave this condition?it will rename the files Again and Again, let me explain.
supposed there is a filename: x.txt
you run the function to rename it with prefix "1_"
the function will check if "1_x.txt" (prefix of "1_" + the filename) already exists.
it will not find, so it will be renamed as "1_x.txt"
you run the function again using same prefix of "1_"
the functon will check if "1_1_x.txt" exists, (remember that
we already renamed x.txt as 1_x.txt, adding another prefix of "1_",
we are now to look if prefix & filename, exists which is "1_" & "1_x.txt")
it will not find, so again it will rename it.