Write a function in python a def merge_sorted(a, b) that merges two sorted lists, returning a new sorted list.

For example, if a is 1, 4, 9, 16 and b is 4, 7, 9, 9, 11 then the function will return a new list containing the values 1, 4, 4, 7, 9, 9, 9, 11, 16

You must not use the sorted() function nor the sort() method. Assume a and b are sorted in ascending order.