How to Debug Python Function Arguments: A Step‑by‑Step Walkthrough

Hi, I’m a Python enthusiast sharing a recent question from a community group about a Python function calculation.

1. Introduction

A user asked why a particular Python function call produced an unexpected result, as shown in the first diagram.

2. Implementation

One instructor provided a solution by decomposing the function, illustrated in the second diagram.

def bar(z, x=0):
    return z + x

def foo(x):
    return bar(3+x)

print(foo(2))

The call bar(3+2) passes only one positional argument ( z), leaving x at its default value 0. The addition 3+2 occurs at the highlighted point in the third diagram.

The value is then passed as shown in the fourth diagram.

To visualize the execution, you can use the online tool Python Tutor , which provides a breakpoint‑like view of the program flow.

If you encounter similar issues, feel free to contact me or join the Python learning group for further assistance.