input: Write a function to solve any Sudoku puzzle given a 9x9 board as a list of lists, where empty cells are represented by 0. The function should print the solved board if there is a solution, otherwise print "No solution".
  assert solve_sudoku([
      [7,8,0,4,0,0,1,2,0],
      [6,0,0,0,7,5,0,0,9],
      [0,0,0,6,0,1,0,7,8],
      [0,0,7,0,4,0,2,6,0],
      [0,0,1,0,5,0,9,3,0],
      [9,0,4,0,6,0,0,0,5],
      [0,7,0,3,0,0,0,1,2],
      [1,2,0,0,0,7,4,0,0],
      [0,4,9,2,0,6,0,0,7]
  ])==None
  assert solve_sudoku([
      [3,0,0,4,0,0,1,2,0],
      [6,0,0,0,0,5,0,0,9],
      [0,0,0,6,0,1,0,7,8],
      [0,0,7,0,4,0,2,6,0],
      [0,0,1,0,5,0,9,3,0],
      [9,0,4,0,6,0,0,0,5],
      [0,7,0,3,0,0,0,1,2],
      [1,2,0,0,0,7,4,0,0],
      [0,4,9,2,0,6,0,0,7]
  ])==None
output: def solve_sudoku(board):
      def is_valid(board, row, col, num):
          for x in range(9):
              if board[row][x] == num or board[x][col] == num or board[row//3*3 + x//3][col//3*3 + x%3] == num:
                  return False
          return True
  
      def solve():
          for row in range(9):
              for col in range(9):
                  if board[row][col] == 0:
                      for num in range(1, 10):
                          if is_valid(board, row, col, num):
                              board[row][col] = num
                              if solve():
                                  return True
                              board[row][col] = 0
                      return False
          return True
  
      if solve():
          for row in board:
              print(row)
      else:
          print("No solution")