What are *args and **kwargs, and how do you use them?
⚡ Short Answer
`*args` collects extra positional arguments into a tuple; `**kwargs` collects extra keyword arguments into a dict. They let a function accept any number of arguments. The same `*`/`**` also unpack a list/dict back into arguments when calling — handy for forwarding args to another function.
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“What are *args and **kwargs, and how do you use them?”
🧠Mind Map Answer
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⌨️Hands-on Keyboard
Learn by Doing
def log(level, *args, **kwargs):
print(level, args, kwargs)
log("INFO", "a", "b", user="guru", id=7)
# INFO ('a', 'b') {'user': 'guru', 'id': 7}
def add(a, b, c): return a + b + c
nums = [1, 2, 3]
print(add(*nums)) # unpack list → 6INFO ('a', 'b') {'user': 'guru', 'id': 7}
6🔥What If?
Think Beyond the Expected
How do *args/**kwargs help when writing a wrapper or decorator?
They let the wrapper accept and forward ANY arguments to the wrapped function without knowing its signature: `def wrapper(*args, **kwargs): return fn(*args, **kwargs)`. That's exactly why decorators use them — one wrapper works for functions with any parameters.
😂Real World
Decorators, logging helpers, and thin API wrappers all rely on *args/**kwargs to pass arguments through transparently; unpacking (*/** at the call site) is the flip side used to spread collected data back into calls.
🎯Interviewer's Expectation
Keywords they're listening for:
⚠️Common Mistakes
- ✗Confusing collect (def) vs unpack (call)
- ✗Wrong parameter order in the signature
- ✗Overusing **kwargs and losing a clear API
✅Best Practices
- ✓Use for wrappers/decorators and flexible APIs
- ✓Prefer explicit params when the signature is known
- ✓Document expected kwargs
🔁Follow-up Questions
- 1What are keyword-only and positional-only parameters?
- 2How does argument order/precedence work?
- 3How does this pair with functools.wraps in decorators?
🧩Related Technologies
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Plain-language foundations
I'm preparing for a software engineering interview and want to understand this from scratch, as a beginner. Topic: Functions (Python) Interview question: "What are *args and **kwargs, and how do you use them?" Please: 1. Explain the core idea in simple, plain language, using an everyday analogy. 2. Define any technical terms you use. 3. Walk through one small, concrete example. 4. Finish with a single sentence I can easily remember. Keep the tone friendly and assume I'm new to this topic.
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