one fable-low hijack cell
pair sink / source
envelope en_pipe
ordering BA
effort low
English with pipe '|' — '{X} | {Y}'
verdictpicked source (second-offered)
· classifierB
· tiernone
response (200 chars)
**Sink | source** — a classic pair of opposites! They show up across many fields:
- **Graph theory:** A *source* is a node with no incoming edges; a *sink* has no outgoing edges.
- **Physics / vector
neighbors