How can I set up a callback function to output each time the acc -

i want output acc @ end of each training session, don't know how use callback function me

this part of code

testing no problem

def train_model():     img_width, img_height = 150, 150     train_data_dir = 'static/train'     validation_data_dir = 'static/validation'     nb_train_samples = 875     nb_validation_samples = 375     epochs = 1     batch_size = 35      model = sequential()     model.add(conv2d(32, (3, 3), input_shape=input_shape))     model.add(activation('relu'))     model.add(maxpooling2d(pool_size=(2, 2)))      model.add(conv2d(64, (3, 3)))     model.add(activation('relu'))     model.add(maxpooling2d(pool_size=(2, 2)))      model.add(flatten())     model.add(dense(64))     model.add(activation('relu'))     model.add(dropout(0.5))     model.add(dense(1))     model.add(activation('sigmoid'))      model.compile(loss='binary_crossentropy',             optimizer='rmsprop',             metrics=['accuracy'])      model.fit_generator(     train_generator,     steps_per_epoch=nb_train_samples // batch_size,     epochs=epochs,     validation_data=validation_generator,     validation_steps=nb_validation_samples // batch_size,     verbose=1)      model.save_weights('my_model_weights.h5')