You can use inbuilt library pickle
This library allows you to save any object in python to a file
This library will maintain the format as well
import pickle
with open('/content/list_1.txt', 'wb') as fp:
pickle.dump(list_1, fp)
you can also read the list back as an object using same library
with open ('/content/list_1.txt', 'rb') as fp:
list_1 = pickle.load(fp)
reference : Writing a list to a file with Python