SKILL.md
Python 3.14+ Expert Best Practices
Simple, pragmatic, opinionated. Only what matters for writing production-grade python code.
When to Apply
Reference these guidelines when:
- Writing Python functions, classes, or modules
- Reviewing Python code for error handling issues
- Refactoring existing Python codebases
- Implementing data validation and API boundaries
- Optimizing error detection and debugging patterns
Rule Categories by Priority
Priority
Category
Impact
Prefix
1
Error Handling
CRITICAL
dict-, operators-
2
Common Bugs
CRITICAL-HIGH
no-mutable-, no-generic-
3
Code Clarity
HIGH-MEDIUM
listcomp-, no-inline-
4
Code Style
LOW
avoid-, unnecessary-
Quick Reference
dict-required-keys- Used[key]for required dictionary keys to fail fast with KeyError
no-mutable-defaults- No mutable defaults in function/method parameters
operators-return-notimplemented- Return NotImplemented for unsupported operand types and design + vs += intentionally
no-generic-except- Avoid generic except clauses to prevent hiding unexpected errors
listcomp-no-side-effects- List comprehensions must produce a value you use (no side-effect listcomps)
no-inline-imports- Place all import statements at the top of the file
avoid-explanatory-comments- Avoid unnecessary comments for self-documenting code
unnecessary-else-blocks- Avoid unnecessary else blocks after return/break/continue statements
How to Use
Read individual rule files for detailed explanations and code examples:
rules/dict-required-keys.md
rules/no-mutable-defaults.md
rules/operators-return-notimplemented.md
rules/no-generic-except.md
rules/listcomp-no-side-effects.md
rules/no-inline-imports.md
rules/avoid-explanatory-comments.md
rules/unnecessary-else-blocks.mdEach rule file contains:
- Brief explanation of why it matters
- When to use and when not to use the pattern
- Implementation requirements
- Incorrect code example with explanation
- Correct code example with explanation
- Additional context and references