AttributeError: 'function' object has no attribute 'predict' while using Alexnet in Keras

I need to use Alexnet model for an image classification task. I took the architecture implementation from this source. I want to apply the model with imagenet weights directly (no finetuning required) and get some predictions for the imageNet dataset. Here is the code:

def alexnet_model(img_shape=(224, 224, 3), n_classes=1000, l2_reg=0.,
weights='/content/drive/My Drive/cbir/models_cnn/alexnet_weights.hdf'):

    # Initialize model
    alexnet = Sequential()

    # Layer 1
    alexnet.add(Conv2D(96, (11, 11), input_shape=img_shape,
    padding='same', kernel_regularizer=l2(l2_reg)))
    alexnet.add(BatchNormalization())
    alexnet.add(Activation('relu'))
    alexnet.add(MaxPooling2D(pool_size=(2, 2)))

    # Layer 2
    alexnet.add(Conv2D(256, (5, 5), padding='same'))
    alexnet.add(BatchNormalization())
    alexnet.add(Activation('relu'))
    alexnet.add(MaxPooling2D(pool_size=(2, 2)))

    # Layer 3
    alexnet.add(ZeroPadding2D((1, 1)))
    alexnet.add(Conv2D(512, (3, 3), padding='same'))
    alexnet.add(BatchNormalization())
    alexnet.add(Activation('relu'))
    alexnet.add(MaxPooling2D(pool_size=(2, 2)))

    # Layer 4
    alexnet.add(ZeroPadding2D((1, 1)))
    alexnet.add(Conv2D(1024, (3, 3), padding='same'))
    alexnet.add(BatchNormalization())
    alexnet.add(Activation('relu'))

    # Layer 5
    alexnet.add(ZeroPadding2D((1, 1)))
    alexnet.add(Conv2D(1024, (3, 3), padding='same'))
    alexnet.add(BatchNormalization())
    alexnet.add(Activation('relu'))
    alexnet.add(MaxPooling2D(pool_size=(2, 2)))

    # Layer 6
    alexnet.add(Flatten())
    alexnet.add(Dense(3072))
    alexnet.add(BatchNormalization())
    alexnet.add(Activation('relu'))
    alexnet.add(Dropout(0.5))

    # Layer 7
    alexnet.add(Dense(4096))
    alexnet.add(BatchNormalization())
    alexnet.add(Activation('relu'))
    alexnet.add(Dropout(0.5))

   # Layer 8
    alexnet.add(Dense(n_classes))
    alexnet.add(BatchNormalization())
    alexnet.add(Activation('softmax'))

    if weights is not None:
      alexnet.load_weights(weights)


    return alexnet.compile()

After that, I run:

model =  alexnet_model
target_size =(224,224)
img = load_img(imagePath, target_size=target_size)
img = img_to_array(img)
img = img.reshape((1, img.shape[0], img.shape[1], img.shape[2]))
img = preprocess_input(img)
y=model.predict(img)[0]

I am getting this error:

AttributeError: 'function' object has no attribute 'predict'