title: Jupyter keep returning nonetype for my digit recognition. i keep getting "'NoneType' object is not subscriptable"
body: <p>What is the problem actually. I saved some picture that i draw with paint and saved in the same folder with the ipynb. i have named th png file as 1,2,3,4,5,6.</p>
  <pre class="lang-py prettyprint-override"><code>import cv2 as cv
  
  import numpy as np
  
  import matplotlib.pyplot as plt
  
  import tensorflow as tf
  
  mnist = tf.keras.datasets.mnist
  
  (x_train, y_train), (x_test, y_test) = mnist.load_data()
  
  x_train = tf.keras.utils.normalize(x_train, axis=1)
  
  x_test = tf.keras.utils.normalize(x_test, axis=1)
  
  model = tf.keras.models.Sequential()
  
  model.add(tf.keras.layers.Flatten(input_shape=(28,28)))
  
  model.add(tf.keras.layers.Dense(units=128, activation=tf.nn.relu))
  
  model.add(tf.keras.layers.Dense(units=128, activation=tf.nn.relu))
  
  model.add(tf.keras.layers.Dense(units=10, activation=tf.nn.softmax))
  
  
  model.compile(optimizer='adam', loss='sparse_categorical_crossentropy', metrics=['accuracy'])
  
  model.fit(x_train, y_train, epochs=3)
  
  accuracy, loss = model.evaluate(x_test, y_test)
  
  print(accuracy)
  
  print(loss)
  
  model.save('digits.model')
  
  for x in range(1,6):
  
      img = cv.imread(f'{x}.png')[:,:,0]
  
      img = np.invert(np.array([img]))
  
      prediction = model.predict(img)
  
      print(f'the result is probably:{np.argmax(prediction)}')
  
      plt.imshow(img[0], cmap=plt.cm.binary)
  
      plt.show
  
  </code></pre>
  <p>[enter image description here][1]</p>
  <p>hope will get help soon
  [1]: <a href="https://i.stack.imgur.com/n6vTs.png" rel="nofollow noreferrer">https://i.stack.imgur.com/n6vTs.png</a></p>