backtracking - NQueens Slver in python -

i making nqueen problem solver every time run program launch error:

"tuple" has no attribute "row"

i want know if function place structure because 1 throw error

import sys #use of argv  #create object queen row , column class queen:     def __init__(self, row, col):         self.row = row         self.col = col      def __repr__(self):         return "row: "+ str(self.row) + " column: " + str(self.col)  #validate if can place queen in space, return false or true def place(board,row,col):     in range(0,len(board)-1):         #attack conditions: cant place in same column, row , diagonal         if (board[i].row == row) or (board[i].col == col) or (abs(board[i].row - row) == abs(board[i].col - col)):             return false     return true  #recursive function append queen board if can place def nqueens(board,n,row):     in range(1,n):         #if row > n fuction return list          if (row > n):             return board          #if can place call nqueens function next row         elif place(board,row,i):             queenaux = (row,i)             board.append(queenaux)             nqueens(board,n,row+1)  #the user enter number of queens , size of board n = int(sys.argv[1]) print("nqueens problem solver") print("chess board: ",n,"x",n) print("number queens:",n) #create list board board = [] #start nqueens function row=1 board = nqueens(board,n,1) #print queens in board , coordinates print (board) 

queenaux = (row,i) board.append(queenaux) 

because of these lines, board contains tuples. must fix making queenaux queen instance, so:

queenaux = queen(row,i) 

also note nqueens doesn't return shouldn't assign board. call function , let modifications.