Write a function, create_linked_list, that takes in a list of values as an argument. The function should create a linked list containing each item of the list as the values of the nodes. The function should return the head of the linked list.

create_linked_list(["h", "e", "y"])
# h -> e -> y

create_linked_list([1, 7, 1, 8])
# 1 -> 7 -> 1 -> 8

create_linked_list(["a"])
# a

create_linked_list([])
# null