Send Schedule Coding Challenge

Design a function that takes a map of strings to strings called send_schedule, where the keys could be 'start', 'end', or numbers. Each user has a corresponding time for these keys. When iterating over users, if a key is 'start' or 'end', handle it separately; otherwise, calculate the corresponding time. Example Input {'start': '2023-10-10 08:00:00', 'end': '2023-10-10 17:00:00', '15': 'some value'}