The Fallback Layer
A easy Python mock interview question on DataDriven. Practice with AI-powered feedback, real code execution, and a hire/no-hire decision.
- Domain
- Python
- Difficulty
- easy
- Seniority
- L3
Interview Prompt
A service builds its runtime config by layering environment values over a baseline. Start from `primary`, the values read from the environment, and keep every key it has; whenever one of those values is `None`, fall back to the same key in `defaults`. A key that lives only in `defaults` never makes it into the result, and a `None` with no matching default stays `None`.
Summary
When the live values come back empty, something has to stand in.
How This Interview Works
- Read the vague prompt (just like a real interview)
- Ask clarifying questions to the AI interviewer
- Write your python solution with real code execution
- Get instant feedback and a hire/no-hire decision