My solution (tictactoeengine.py) for 'Tic Tac Toe Game' exercise on practicepython.org -> http://www.practicepython.org/exercise/2016/08/03/28-tic-tac-toe-game.html

gameboardtoscreen.py

"""Functions for printing a TicTacToe gameboard to the console
	
	The gameboard should be represented as a 2 dimensional list of 3 rows and 3 columns
"""

element_process = lambda i: ("X" if i == 1 else ("O" if i == 2 else " "))

def printboard(board):
	print "\n game = [%s]\n" % ",\n\t ".join(["[%s]" % ", ".join(map(element_process, board[i])) for i in xrange(3)])

tictactoecheck.py

"""Determine the winner of any of a game of tic tac toe
	
	The results of the play woll be provided to the program as a
	2 dimensional array of 3 lists which will contain numbers
	indicating the mark on that spot on the board.
	
		1 will represent play by player 1
		2 represent play by player 2
		0 inicates a blank cell
"""

def determine_winner(board):
	"""Returns 0 if there's no winner, 1 or 2 if there's a winnner
		
		As 1 and 2 represent plays by player 1 and player 2 respectively,
		1 or 2 is returned if either player wins.
	"""
	
	#check forward diagonal
	if board[0][0] == board[1][1] == board[2][2]:
		return board[0][0]
	#check backward diagonal
	elif board[0][2] == board[1][1] == board[2][0]:
		return board[0][2]
	
	#check verticals
	for i in xrange(3):
		if board[0][i] == board[1][i] == board[2][i]:
			return board[0][i]
	
	#check horizontals last as they are least likely to win
	for i in xrange(3):
		if board[i][0] and (board[i][0] == board[i][1] == board[i][2]):
			return board[i][0]
	
	return 0

if __name__ == "__main__":
	testboard = [[1,2,2], [2,2,0], [2,1,1]]
	
	winner = determine_winner(testboard)
	if winner:
		print "Player %d won." % winner
	else:
		print "Draw!"

tictactoeengine.py

"""Game engine for Tic Tac Toe game.
	
	These functions only initialise and organise the game as well as keep the scores
	of players
"""

from tictactoeplay import play_game

def play():
	"""Handle the initialising of games and keeping score"""
	Player1wins = Player2wins = games = 0
	
	do_play = raw_input("Do you wish to play a game of Tic Tac Toe? (y/n) : ").lower()
	if "y" in do_play:
		while 1:
			games += 1
			winner = play_game()
			
			if winner:
				if winner == 1:Player1wins += 1
				elif winner == 2: Player2wins += 1
				
				print "\nPlayer %d wins.\n" % winner
			
			else: print "\nDraw!\n"
			print "\tGames Played\tPlayer 1 wins\tPlayer 2 wins\n\t	%d\t	%d	\t%d" % (games, Player1wins, Player2wins)
			
			again = raw_input("\nWould you like to play again? (y/n) : ").lower()
			if "y" in again:
				continue
			else: break
		
if __name__ == "__main__":
	play()

tictactoeplay.py

"""A basic tictactoe game to be played from the console

	Input of the game will be entered as coordinates of the form (x,y)
	where x is the row and y the column and they are both numbers
	with a minimum number of 1 and a maximum of 3
"""

import tictactoecheck as gamechecker
import gameboardtoscreen as gameprinter

def introduceplayers():
	"""Prints a text file that contains introductory information about the game.
	
		Information in the file includes instructions on how to play the game."""
	with open("gameintro.txt", 'r') as f:
		print f.read()
		
def get_playermove(player):
	"""Processes return it as a tuple of coordinates.
	
		If the input is invalid in any way that will affect the game
		The player is notified and the function repeats recursively"""
	
	rr = raw_input("\nPlayer %d >> " % player)
	move = rr.split(",")
	try:
		#if coordinates were actually entered
		if len(move) != 2:
			move = rr.split()
			if len(move) != 2:
				raise ValueError
		x, y = int(move[0]), int(move[1])
		
		#the coordinates be within range
		if all((0 < x < 4, 0 < y < 4)):
			return (x, y)
		else:
			print "\nThe first column or row is 1 and the final is 3"
			print "Please re-enter correctly."
			return get_playermove(player)
	except ValueError:
		#if coordinates not entered or not integers
		print "Please enter only the row and column as numbers separated by a comma eg(1, 1)"
		return get_playermove(player)

def play_game():
	"""Handle playing of Tic Tac Toe game"""
	
	introduceplayers()
	
	#just for fun
	board = [[0 for j in xrange(3)] for i in xrange(3)]
	free_slots = 9
	
	a, b = 1, 2
	
	winner = 0
	while free_slots and not winner:
		playermove = get_playermove(a)
		while board[playermove[0]-1][playermove[1]-1]:
			#prevent playing a move that's already played
			print "\nThat move has already been played. Please play another."
			playermove = get_playermove(a)
		
		board[playermove[0]-1][playermove[1]-1] = a
		free_slots -= 1
		a, b = b, a
		
		#print the game to the screen
		gameprinter.printboard(board)
		
		if (9 - free_slots) >= 5:
			#minimum number of moves that can be made for any player to win is 5
				#so start checking for a winner after 5 moves
			winner = gamechecker.determine_winner(board)
		
	
	return winner