Python Coding Challange - Question with Answer (01220525)

 

Key Concepts:

🔹 lst=[] is a mutable default argument.

• In Python, default argument values are evaluated only once when the function is defined, not each time it’s called.

• That means the same list (lst) is reused across multiple calls unless a new one is explicitly provided.

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Step-by-Step Execution:

First Call:

append_item(1)

val = 1

• No list is passed, so lst defaults to []

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

• It returns [1]

Second Call:

append_item(2)

val = 2

• Still using the same list as before ([1])

• 2 is appended → list becomes [1, 2]

• It returns [1, 2]

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✅ Output:

[1]
[1, 2]

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 How to Avoid This Pitfall:

To make sure a new list is used for each call, use None as the default and create the list inside the function:

def append_item(val, lst=None):
    if lst is None:
       lst = []
    lst.append(val)     
    return lst

Now each call will work with a fresh list.

APPLICATION OF PYTHON IN FINANCE

https://pythonclcoding.gumroad.com/l/zrisob