def changiling(self, infile):
        '''Changiling: 任意のバイト文字を 他の任意のバイト文字に置き換える
        '''
        gf = infile[31:]
        baby, fetch = (self.word_toaster() for _ in range(2))
        gf = [g.replace(baby, fetch) for g in gf]
        return infile[:31] + gf