A simple python command line tic tac toe game

tictactoe.py

import pprint

# Returns a row in a given column
def column(matrix, i):
    return [row[i] for row in matrix]

# Checks if a given row or column has all of the same value
def check(list):
    if len(set(list)) <= 1:
        if list[0] != 0:
            return list[0]
    return None

def checkDiagLeft(board):
    if (board[0][0] == board[1][1] and board[1][1] == board[2][2]):
        if board[0][0] != 0:
            return board[0][0]
    return None

def checkDiagRight(board):
    if (board[2][0] == board[1][1] and board[1][1] == board[0][2]):
        if board[2][0] != 0:
            return board[2][0]
    return None

def placeItem(row, column, board, current_player):
    if board[row][column] != 0:
        return None
    else:
        board[row][column] = current_player

def swapPlayers(player):
    if (player == 2):
        return 1
    else:
        return 2

# checks if any player has won the game
def winner(board):
    for rowIndex in board:
        if check(rowIndex) is not None:
            return check(rowIndex)
    for columnIndex in range(len(board[0])):
        if check(column(board, columnIndex)) is not None:
            return check(column(board, columnIndex))
    if checkDiagLeft(board) is not None:
        return checkDiagLeft()
    if checkDiagRight(board) is not None:
        return checkDiagRight(board)
    return 0

def getLocation():
    location = raw_input("Choose where to play. Enter two numbers seperated by a comma, for example: 1,1 ")
    coordinates = map(int, location.split(','))
    while (len(coordinates) != 2 or coordinates[0] < 0 or coordinates[0] > 2 or coordinates[1] < 0 or coordinates[1] > 2):
        print "You inputted a location in an invalid format"
        location = raw_input("Choose where to play. Enter two numbers seperated by a comma, for example: 1,1 ")
        coordinates = map(int, location.split(','))
    return coordinates

def gamePlay():
    num_moves = 0;
    pp = pprint.PrettyPrinter(width=20)
    current_player = 1
    board = [[0 for x in range(3)] for x in range(3)]

    while (num_moves < 9 and winner(board) == 0):
        print "This is the current board: "
        pp.pprint(board)
        coordinates = getLocation();
        placeItem(coordinates[0], coordinates[1], board, current_player)
        current_player = swapPlayers(current_player)
        if winner(board) != 0:
            print "%s won!" % winner(board)
        num_moves += 1
    print "There is no winner, the game is over!"

gamePlay()