':type s: str
:rtype: str'

def reverseString(self, s):

    string = list(s)
    (i, j) = (0, (len(string) - 1))
    while (i < j):
        (string[i], string[j]) = (string[j], string[i])
        i += 1
        j -= 1
    return ''.join(string)
