# create a new list (length is 1 less)
# and contains the sum of consecutive values in original list

def consecutive_values(alist):
    newlist = []

    # if alist is length 4
    # i becomes: 0, 1, 2
    for i in range(len(alist) - 1):
        newlist.append(alist[i] + alist[i+1])

    return newlist


mylist = [10,8,13,-3]
print(mylist)
conslist = consecutive_values(mylist)
print(conslist)