I implemented this by reading about Kadane’s algorithm for sum of subsequences

def kadane(arr):
    max_current = arr[0]
    globalSum = 0
    for x in arr[1:]:
        max_current = max(x, max_current + x)
        globalSum = max(globalSum, max_current)
    return globalSum

But for
arr4 = [1, 400, 7, -2, 0, 15]
the subarray should be 1+400+7+0+15, without the -2, giving 423 as answer. Moreover when I run I have 421 as answer because it considers the -2.

Any idea where I got lost?