(I need help programming this code. If you can do it in Scala, that would be great. If not, Python works too. Thank you.)

Write a tail recursive function sumUpEvenIndices that given a list of integers List() returns the sum of all elements at even numbered indices.

Corner Cases

-Empty list must return 0.

-List with just one element must return that element.

Restrictions

-Must be tail recursive.

-Allowed list API functions/operations: list.length, list.head, list.tail.

+All other operations over lists disallowed.

-Do not try to convert the list into an array or some other data structure.

-Use of vars/loops is not allowed.

Note: ??? indicates that there is a missing function or code fragment that needs to be filled in. In scala, it is also a macro that throws a NotImplemented exception. Make sure that you remove the ??? and replace it with the answer.

###CODE

import scala.annotation.tailrec @tailrec // YOUR CODE HERE ???

//BEGIN TEST

val t1 = sumUpEvenIndices(List(5, 10, 12, -3) ) assert( t1 == 17, s"Test1 failed: expected answer 17, got: $t1")

val t2 = sumUpEvenIndices(List() ) assert( t2 == 0, s"Test2 failed: expected answer 0, got: $t2")

val t3 = sumUpEvenIndices(List(-3) ) assert( t3 == -3, s"Test3 failed: expected answer -3, got: $t3")

val t4 = sumUpEvenIndices(List(0, 1, 0, 5, 0, 9, 0, 12, 0, -45, 0, -56) ) assert( t4 == 0, s"Test4 failed: expected answer 0, got: $t4")

val t5 = sumUpEvenIndices(List(11, 0) ) assert( t5 == 11, s"Test5 failed: expected answer 11, got: $t5")

passed(7)

//END TEST