input: def transpose(A):
      """
      Optimize a Python program that processes a 2d array and stores the transpose output in a new array.
      >>> transpose([[1, 2, 3], [4, 5, 6]])
      [[1, 4], [2, 5], [3, 6]]
      >>> transpose([[1, 2], [3, 4], [5, 6]])
      [[1, 3, 5], [2, 4, 6]]
      """
      return [list(row) for row in zip(*A)]
output:     return [list(row) for row in zip(*A)]