text: import numpy as np
  from keras.models import Sequential
  from keras.layers import Dense, Conv2D, Flatten,MaxPooling2D
  import matplotlib.pyplot as plt
  
  def Emotion_classification_CNN():
      #4.build model by keras
      model = Sequential()
      #add model layers
      model.add(Conv2D(32, kernel_size=5, activation='relu', input_shape=(48,48,1)))
      model.add(MaxPooling2D(pool_size=(3, 3), strides=(2, 2)))
      model.add(Conv2D(64, kernel_size=4, activation='relu'))
      model.add(MaxPooling2D(pool_size=(3, 3), strides=(2, 2)))
      model.add(Conv2D(128, kernel_size=3, activation='relu'))
      model.add(MaxPooling2D(pool_size=(3, 3), strides=(2, 2)))
      model.add(Flatten())
      model.add(Dense(256, activation='relu'))
      model.add(Dense(7, activation='softmax'))
      model.compile(optimizer='adam', loss='categorical_crossentropy', metrics=['accuracy'])
      return model