Whenever you pass two arrays (or any number of arrays for that matter)
as arguments to a function, what happens is they get flattened and
become a single list and then it is assigned to _.
So when U say
array1 has the entire _ (which is now having a single list that was
constructed with the 2 arrays passed to the function)
For example when you have a piece of code like
arr1 = ("Sun", "Mon");
arr2 = ("Tue", "Wed");
arr3 = (arr1, arr2);
Now arr3 has a single list with Sun, Mon, Tue and Wed as ...