Menu
For graceful failure: return None or False instead of exceptions, let caller decide how to handle failure.
Install with Codex or Claude Copy this prompt, paste it into Codex, Claude, or another assistant, and let it review the skill page and install it for you.
Based on SOC occupation classification
| name | return-none-for-failure |
| description | For graceful failure: return None or False instead of exceptions, let caller decide how to handle failure. |
Return None (or False) to indicate failure, let caller check.
def find(items, predicate):
"""Find first item matching predicate, or None."""
for item in items:
if predicate(item):
return item
return None # Not found
# Caller checks
result = find(items, is_valid)
if result is not None:
process(result)
else:
handle_not_found()
# Sudoku solver (sudoku.py)
def search(values):
"""Using depth-first search and propagation."""
if values is False:
return False # Failed earlier
if all(len(values[s]) == 1 for s in squares):
return values # Solved!
# Choose unfilled square with fewest possibilities
n, s = min((len(values[s]), s)
for s in squares if len(values[s]) > 1)
for d in values[s]:
result = search(assign(values.copy(), s, d))
if result: # Found solution
return result
return False # No solution found
# Constraint propagation
def eliminate(values, s, d):
"""Return values, or False if contradiction detected."""
if d not in values[s]:
return values # Already done
values[s] = values[s].replace(d, '')
if len(values[s]) == 0:
return False # Contradiction
# ... more propagation
return values
# Usage pattern
solution = solve(puzzle)
if solution:
display(solution)
else:
print("No solution exists")
# Cryptarithmetic (Cryptarithmetic.ipynb)
def first(iterable):
"""First element of iterable, or None."""
return next(iter(iterable), None)
solution = first(solve('SEND + MORE = MONEY'))
if solution:
print(solution)
if: Natural control flowif result is False: return Falseif result: catches None/FalseConducts iterative deep research on any topic using web search, progressive exploration, and structured synthesis. Use when asked for comprehensive research, deep investigation, thorough analysis, or multi-source exploration of any topic. Triggers: research, investigate, deep dive, comprehensive analysis, explore thoroughly, find everything about.
For cross-cutting concerns: add behavior without modifying functions, caching, timing, logging, validation wrappers.
For performance work: measure before changing, profile to find bottlenecks, compare before and after.
For symbolic computation: ASTs, mathematical expressions, code that manipulates code structure, expression transformations.
For ordered processing: A* search, Dijkstra, event simulation, task scheduling. Efficient min/max extraction with heap-based queue.
For dynamic programming: overlapping subproblems, recursive solutions with repeated computations, memoization to avoid redundant work.