这两个代码运行错误怎么解决，感觉完完全全按照老师打的呀

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NameError                                 Traceback (most recent call last)

<ipython-input-24-83d76d986e7e> in <module>()

----> 1 ppn = Perceptron(eta=0.1, n_iter=10)

      2 ppn.fit(X,y)

      3 plt.plot(range(1,len(ppn.errors_) + 1), ppn.errors_, marker='o')

      4 plt.xlabel('Epochs')

      5 plt.ylabel('错误分类次数')

NameError: name 'Perceptron' is not defined

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NameError                                 Traceback (most recent call last)

<ipython-input-22-6d6859494f47> in <module>()

----> 1 plot_decision_regions(X, y, ppn, resolution=0.02)

NameError: name 'ppn' is not defined