input: Write a function to optimize a Python program that processes a 2d array and stores the transpose output in a new array.
  
  assert transpose([[1,2,3],[4,5,6],[7,8,9]])==[[1,4,7],[2,5,8],[3,6,9]]
  assert transpose([[1,2],[3,4],[5,6]])==[[1,3,5],[2,4,6]]
  assert transpose([[1],[2],[3]])==[[1,2,3]]
  assert transpose([[1,2,3]])==[[1],[2],[3]]
  assert transpose([[]])==[[]]
output: def transpose(matrix):
      return [list(row) for row in zip(*matrix)]