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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def validate_schedule():
 """Helper routine to report issues with the schedule"""

    all_items = prefetch_schedule_items()
    errors = []
    for validator, _type, msg in SCHEDULE_ITEM_VALIDATORS:
        if validator(all_items):
            errors.append(msg)

    all_slots = prefetch_slots()
    for validator, _type, msg in SLOT_VALIDATORS:
        if validator(all_slots):
            errors.append(msg)
    return errors