Write a function that takes three arguments, 2 arrays (a and b) and 1 integer (c) then returns one array (d) which is created by inserting all elements in b into a at indexes which are spaced by the integer value.

Consider all possible corner cases.
e.g
a = ["a", "b", "c", "d", "e", "f"]
b = ["1", "2", "3"]
c = 2

d = ["a", "b", "1", "c", "d", "2", "e", "f", "3"]