one fable-low hijack cell
pair pure / side_effecting
envelope en_arrow
ordering BA
effort low
English with arrow '→' — '{X} → {Y}'
verdictpicked side_effecting (second-offered)
· classifierB
· tiernone
response (200 chars)
# Side-Effecting → Pure: Refactoring Patterns
The core idea: **push effects to the edges, return data instead of doing things.**
## 1. Return values instead of mutating
```python
# Side-effecting
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neighbors