python 'list' object has no attribute 'deepcopy'

This error occurs when you try to use the `deepcopy()` method on a list object in Python.

The `deepcopy()` method is used to create a new object with a completely separate copy of the original object and all of its nested objects. However, lists in Python are not considered to be nested objects, so they do not have a `deepcopy()` method.

Instead, you can use the `copy()` method to create a shallow copy of the list, or you can create a new list using list comprehension or slicing.

Here's an example of how to use `copy()`:

my_list = [1, 2, 3, [4, 5]]
new_list = my_list.copy() # shallow copy

# make changes to new_list
new_list[0] = 10
new_list[3].append(6)

# original list is unchanged
print(my_list) # [1, 2, 3, [4, 5]]
print(new_list) # [10, 2, 3, [4, 5, 6]]

If you need to create a deep copy of a list, you can use the `copy` module's `deepcopy()` function:

import copy

my_list = [1, 2, 3, [4, 5]]
new_list = copy.deepcopy(my_list) # deep copy

# make changes to new_list
new_list[0] = 10
new_list[3].append(6)

# original list is unchanged
print(my_list) # [1, 2, 3, [4, 5]]
print(new_list) # [10, 2, 3, [4, 5, 6]]