# Write a function that takes two lists of integers,
# sum the two lists together and return the resulting list.
# For example if the two lists are [1,2,3] and [4,5,6,7],
# your code would return [5, 7, 9, 7]
#
# Do not use any built-in functions
# except len(), remove(), and append()
#

def sumLists(l1,l2):
   result = []

   for i in range(len(l2)):
      if i < len( l1):
         l1[i] += l2[i]
      else:
         l1.append(l2[i])

   result = l1

   return result


print(sumLists([], []))      # expected []
print(sumLists([1], [2]))    # expected [3]
print(sumLists([], [1]))     # expected [1]
print(sumLists([1], []))     # expected [1]
print(sumLists([2,7,3,1,9,5,5,4,6,8], [3,2,1]))     # expected [5, 9, 4, 1, 9, 5, 5, 4, 6, 8]