LENGTH -> The desired length of the output string (INTEGER)
SET -> The desired characters that will compose the output string (STRING)
lenght of SET to the power of LENGTH
Example: If you function call looks like this: randString(5, "ABC")
The formula will be:
3 to the power of 5
As the length of SET is 3 and LENGTH is 5.
The amount of unique possible strings will be 243
The output strings will be 5 characters long and will contain only "A", "B" or "C"
Examples:
ABCBA
ABACB
ABCCB