Hello everyone please help what could i be doing wrong here Im getting this error

Question

# load image and store it numpy array 

# empty list to store images 

X = []

# iterating over each image

for img_name in data1.image_names:

  # loading the image using its name

  img1 = plt.imread('/content/images/' + img_name)

  #img = plt.imread('/content/drive/MyDrive/images/' + '10205.jpg')

  # saving each image in the list

  X.append(img1)

  # converting the list of images into array

  X=np.array(X)

  # storing the target variable in separate variable 

  y = data1.class1_male_or_female.values

Error: 

AttributeError                            Traceback (most recent call last)

<ipython-input-13-b131471561a9> in <module>()
      9   #img = plt.imread('/content/drive/MyDrive/images/' + '10205.jpg')
     10   # saving each image in the list
---> 11   X.append(img1)
     12 
     13   # converting the list of images into array

AttributeError: 'numpy.ndarray' object has no attribute 'append'