Reposition the file pointer.

def seek(self, offset, whence=SEEK_SET):
        """Reposition the file pointer."""

        if whence == SEEK_SET:
            self.__sf.seek(offset)
        elif whence == SEEK_CUR:
            self.__sf.seek(self.tell() + offset)
        elif whence == SEEK_END:
            self.__sf.seek(self.__sf.filesize - offset)