input: Write a function to optimize a Python program that processes a 2d array and stores the transpose output in a new array. The function should accept a 2D array as input and return its transpose.
  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]]) == [[1]]
  assert transpose([[1, 2, 3]]) == [[1], [2], [3]]
  assert transpose([[1], [2], [3]]) == [[1, 2, 3]]
output: def transpose(matrix):
      return [[matrix[j][i] for j in range(len(matrix))] for i in range(len(matrix[0]))]