Please explain code

Question

Why the output of this code is [8,0,4] ?

arr=[(5,8,0), (2,4)] # is this an array list or a list of tuples?
sum = [] # I don't like when people give function builtin names to object ...
for x, *y in arr: # please explain the syntax '*y' what does the * before y mean?
sum=sum+y
print(sum)

Answer 1

With this code, what happens is that the loop will cycle through both tuples within the array, setting the first value of the tuple to x and setting any other value following it to y (hence the weird syntax when declaring it). Once y gets its value (first being [8,0] and then being [4]), it gets pushed to the end of the of the sum array, resulting in the [8,0] and [4] being combined into one single array.