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How do you use the traceback module to capture and format a full exception traceback as a string, useful for logging? How do you use the timeit module to accurately measure a small code snippet's execution time? How do you use cProfile to identify which functions are consuming the most time in a larger program? How do assert statements work for debugging, and why should they NOT be relied upon for production input validation? How would you use the 'faulthandler' module to diagnose a program that crashes with a segmentation fault, typically from a C extension? How do you use memory_profiler (or tracemalloc from the standard library) to identify a memory leak's source in a Python application? How would you use the 'logging' module's exception logging (logger.exception()) INSIDE an except block to automatically capture the full traceback? How do you use pdb's post-mortem debugging mode to inspect a program's state exactly at the point where an unhandled exception occurred? How would you profile memory allocations specifically (not just CPU time) to find which objects are consuming the most memory in a running process? How do you use conditional breakpoints in pdb to pause execution only when a specific condition is met, avoiding manually stepping through many unrelated iterations?
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How do you use Python's built-in 'warnings' module to surface deprecated or risky code paths during debugging?

Intermediate

Answer

warnings.warn(message, category) emits a runtime warning without stopping execution, and running Python with -W error (or filterwarnings('error')) turns warnings into exceptions during testing, helping catch deprecated API usage before it becomes a hard failure in a future version.
import warnings

def old_function():
    warnings.warn("old_function is deprecated, use new_function instead", DeprecationWarning)
    return new_function()

# During testing: python -W error::DeprecationWarning script.py  -- turns the warning into an exception
Real-world example Flagging a deprecated internal API during a migration so callers get an early, non-fatal signal to update before it's removed.

Common follow-ups: How do you configure a custom warnings filter to show a warning only once, instead of every time it's triggered?

Exception Handling
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