My solution for 'Tic Tac Toe Draw' exercise on practicepython.org ->http://www.practicepython.org/exercise/2015/11/26/27-tic-tac-toe-draw.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)])

gameintro.txt

This is a basic game of Tic Tac Toe

The game will take place on a board such as
	    1  2  3
	[1 [0, 0, 0],
	 2 [0, 0, 0],
	 3 [0, 0, 0]]
		
On the board player 1 will be represented by X and player 2 by O
Enter moves in a comma separated sequence or row and column ie row, column

e.g. Player 1 entering '1, 3' will result in 
		  [[ ,  , X],
		   [ ,  ,  ],
		   [ ,  , ]]

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!"

ticttactoeplay.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)
		
	if winner: print "\nPlayer %d wins.\n" % winner
	else: print "\nDraw!\n"

if __name__ == "__main__":
	play = raw_input("Do you wish to play a game of Tic Tac Toe? (y/n) : ").lower()
	if "y" in play:
		play_game()