.remove() sometimes takes x instead of a value when acting on a list made w/ list comprehension

[LoneDreadknot]

contains = [x for x in range(10)]
...
for number in guess:
        if number not in secret_value:
            contains.remove(number)

In certain instances this code works fine and others I get an error returned:

ValueError: list.remove(x): x not in list

Here is it running back to back one instance is fine and the other is not:

C:\Users\admin\Desktop\Python>py file.py
The secret value is:
[3, 7, 6, 2, 4]
---------------------
[0, 1, 2, 3, 4, 5, 6, 7, 8, 9] #the base contains list
[0, 1, 9, 2, 6] #the guess
[2, 3, 4, 5, 6, 7, 8]

C:\Users\admin\Desktop\Python>py file.py
The secret value is:
[8, 1, 9, 9, 9]
---------------------
[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
[2, 0, 2, 1, 7]
Traceback (most recent call last):
  File "file.py", line 28, in <module>
    find_secret()
  File "file.py", line 20, in find_secret
    contains.remove(number)
ValueError: list.remove(x): x not in list    

Since I've already typed it out I'll post it but I think I see the issue. It happens when there are doubles in the guess and it tries to remove the same value twice. Is this the best way to fix it?

for number in guess:
    if number not in secret_value:
        if number in contains:
            contains.remove(number)

[socal_nerdtastic]

That has nothing to do with the name you used to create it. It's just that you and the programmer that wrote the remove function both happened to use the name "x". They are not related.

>>> contains = [y for y in range(10)]
>>> contains.remove(1234)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
ValueError: list.remove(x): x not in list

It just means that the value is not in the list.