Python: TypeError: unsupported operand type(s) for +=: 'int' and 'NoneType'


#1

Could someone help me with this?

def collision():
    points = 0
    for bub in range(len(bub_id)-1, -1, -1):
        if distance(ship_id2, bub_id[bub]) < (SHIP_R + bub_r[bub]):
            points += (bub_r[bub] + bub_speed[bub])
            del_bubble(bub)
        return points

score = 0
**_score = score + collision()_**     #This is what's failing for me
print(score)

#2

Could you show me the List/Dictionary bub_r and bub_speed