<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def bootstrap(self):
 """ Return a new Alignment that is a bootstrap replicate of self """

        new_sites = sorted(sample_wr(self.get_sites()))
        seqs = list(zip(self.get_names(), (''.join(seq) for seq in zip(*new_sites))))
        return self.__class__(seqs)