def succ(src: String): String = ???

assert(succ("") == "")
assert(succ("R2D3") == "R2D4")
assert(succ("R2D9") == "R2E0")
assert(succ("A99") == "B00")
assert(succ("Z99") == "AA00")
assert(succ("Zz99") == "AAa00")
assert(succ("9Z") == "10A")

def firstPrimeGreatThan(num: Int): Int = ???

assert(firstPrimeGreatThan(4) == 5)
assert(firstPrimeGreatThan(20) == 23)
assert(firstPrimeGreatThan(100) == 101)