Python Coding challenge - Day 489| What is the output of the following Python Code?

 

Code Explanation:

 1. Function Definition

def append_to_list(value, my_list=[]):

Function Name: append_to_list

Parameters:

value: The item to add to the list.

my_list=[]: A default mutable argument, which is a list. This is the key part to focus on.

Important: Default values like [] are only evaluated once when the function is defined, not every time it’s called.

 2. Function Body

    my_list.append(value)

Adds the value to the my_list.

If no list is passed in, it appends to the default list (which is reused between calls).

    return my_list

Returns the updated list after appending the value.

3. First Function Call

print(append_to_list(1))

No list is provided, so the default list [] is used.

1 is appended to the list → list becomes [1].

Output:

[1]

4. Second Function Call

print(append_to_list(2))

Again, no list is provided.

But here's the catch: the same default list from the first call is reused.

2 is appended to the existing list [1], making it [1, 2].

Output:

[1, 2]

5. Final Output

[1]

[1, 2]