Calculate the sum of the largest continuous integers in an array

calculate_subset.py

def calculate_subs(_list):
    totals = []
    index = 0
    first_val = True
    for i in _list:
        if first_val:
            totals.append(i)
            first_val = False
        else:
            if i - prev == 1:
                totals[index] += i
            else:
                index += 1
                totals.append(i)
        prev = i
    return totals


def main():
    _input = [5, 4, 6, 7, 8, 6, 7, 6, 8, 9, -10, -9, 2, 3, 4, 5, 6]
    totals = calculate_subs(_input)
    biggest = totals[0]
    for i in totals:
        if i > biggest:
            biggest = i

    print(_input)
    print(totals)
    print(biggest)


if __name__ == '__main__':
    main()

$ python calculate_subset.py
[5, 4, 6, 7, 8, 6, 7, 6, 8, 9, -10, -9, 2, 3, 4, 5, 6]
[5, 4, 21, 13, 6, 17, -19, 20]
21