'setto(s) sets (j+1),...k to the characters in the string s,
readjusting k.'

def setto(self, s):

    length = len(s)
    self.b = ((self.b[:(self.j + 1)] + s) + self.b[((self.j + length) + 1):])
    self.k = (self.j + length)
