The following problem occurs when I am drawing a picture：

MatplotlibDeprecationWarning: Adding an axes using the same arguments as a previous axes currently reuses the earlier instance.  In a future version, a new instance will always be created and returned.  Meanwhile, this warning can be suppressed, and the future behavior ensured, by passing a unique label to each axes instance.
warnings.warn(message, mplDeprecation, stacklevel=1)

My program is as follows：
plt.ion()   # interactive mode
for i in range(64):
    ax = plt.subplot(8, 8, i + 1)
    #ax.set_title('Sample #{}'.format(i))
    ax.axis('off')
    plt.imshow(y[0].data.cpu().numpy()[0,i,:,:],cmap='jet')
    plt.show()
    plt.savefig('feature.png')

How can I solve it?
plt.ioff()
plt.show()