input: Write a Python function that separately combines the first and last items in each sublist of a list of lists.
  assert merge([['x', 'y'], ['a', 'b'], ['m', 'n']]) == [['x', 'a', 'm'], ['y', 'b', 'n']]
  assert merge([[1, 2], [3, 4], [5, 6], [7, 8]]) == [[1, 3, 5, 7], [2, 4, 6, 8]]
  assert merge([['x', 'y', 'z'], ['a', 'b', 'c'], ['m', 'n', 'o']]) == [['x', 'a', 'm'], ['y', 'b', 'n'], ['z', 'c', 'o']]
output: def merge(lists):
      combined = []
      for i in range(len(lists[0])):
          combined.append([sublst[i] for sublst in lists])
      return combined