Which problems are reported before 1978-06-26? Give me the ids of the problems.
SELECT problem_id FROM problems WHERE date_problem_reported < "1978-06-26"
SELECT problem_id FROM problems WHERE date_problem_reported < "1978-06-26"
[{'problem_id': 4}, {'problem_id': 8}, {'problem_id': 11}, {'problem_id': 12}, {'problem_id': 13}, {'problem_id': 14}, {'problem_id': 15}]