Readiness

"""Optional readiness diagnostic. Do not read solutions first.
Run: python check_readiness.py
"""
def sum_positive(values):
    raise NotImplementedError

def with_added_item(items, item):
    """Return a new list; preserve the input list."""
    raise NotImplementedError

def mean_minutes(values):
    """Raise ValueError on empty input."""
    raise NotImplementedError

def parse_minutes(raw):
    """Convert integer text; reject negative values with ValueError."""
    raise NotImplementedError