input: Write a python function to create a 3x3 matrix with consecutive numbers starting from 1.
  assert create_matrix(3) == [[1, 2, 3], [4, 5, 6], [7, 8, 9]]
  assert create_matrix(2) == [[1, 2], [3, 4]]
  assert create_matrix(4) == [[1, 2, 3, 4], [5, 6, 7, 8], [9, 10, 11, 12], [13, 14, 15, 16]]
output: def create_matrix(n):
      return [[n * i + j + 1 for j in range(n)] for i in range(n)]