Implement `top_error_ips(lines, n=3)` for nginx-style log lines. Run it three times so we cover both boundaries plus the canonical case: 1. canonical sample (8 lines, mixed 5xx/2xx) with n=3 → top 3 error IPs 2. empty list with n=3 → empty result (boundary: no input) 3. canonical sample with n=1 → top 1 only (boundary: small n) Print each result on its own line. Expected: [('10.0.0.5', 3), ('10.0.0.7', 2), ('10.0.0.1', 1)] [] [('10.0.0.5', 3)]