def sum(n):
    """Computes the sum of all integers between 1 and n, inclusive.
    Assume n is positive.

    >>> sum(1)
    1
    >>> sum(5)  # 1 + 2 + 3 + 4 + 5
    15
    """
    if n == 0:
        return 0
    return sum(n - 1) + n

print(sum(5))
