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| class_id | teacher_id | starts_at | ends_at |
|---|---|---|---|
| 40 | 20 | 18:00:00 | 21:00:00 |
| 41 | 59 | 18:00:00 | 21:00:00 |
| 42 | 21 | 18:30:00 | 20:00:00 |
| 43 | 80 | 18:30:00 | 21:00:00 |
| 44 | null | 17:30:00 | 21:00:00 |
| 45 | 140 | 17:30:00 | 20:00:00 |
| 46 | 123 | 18:30:00 | 21:00:00 |