input: Write a python function to create a neural network in Python to recognize the handwritten digits from 0 to 9.
  assert isinstance(create_neural_network(), tf.keras.Sequential)
  assert create_neural_network().output_shape == (None, 10)
  assert create_neural_network().layers[1].units == 256
output: def create_neural_network():
      import tensorflow as tf
      from tensorflow.keras import layers, models
  
      model = models.Sequential()
      model.add(layers.Flatten(input_shape=(28, 28)))
      model.add(layers.Dense(256, activation='relu'))
      model.add(layers.Dense(10, activation='softmax'))
  
      return model