Complete the function magical_string(), strictly in python3 language only.

everything is clearly mentioned in the pic attached. kindly consider the constraints as well as multiple hidden test cases need to be passed

Magical string You are given the following: S String consisting of only uppercase English alphabets You want to convert string Sinto a Magical string that has either of the following propertiest All the characters in the string consist of either A or B. . There exists index i such that 1 Si