silmal hoon school 101 week 3 part 2

:: Define a naked gate that takes a list of atoms.
:: I used * because I couldn't figure out what was the 'type' of a list.
::
|=  n=*
:: Initialize i with value 1.
::
=/  i=@ud  1
:: Set a recursion point to loop over the list elements.
::
|-
:: Check if i == 3; if so, return the head of our list.
::
?:  =(i 3)
  -:n
:: Otherwise, recur with the tail of our list after incrementing i.
::
$(n +:n, i (add 1 i))