Simple text-based Tic Tac Toe implementation. I have no idea why I made this.

tictactoe.py

#!/usr/bin/env python3

# tictactoe by David Hoppenbrouwers
#
# To the extent possible under law, the person who associated CC0 with
# David Hoppenbrouwers has waived all copyright and related or neighboring rights
# to David Hoppenbrouwers.
#
# You should have received a copy of the CC0 legalcode along with this
# work.  If not, see <http://creativecommons.org/publicdomain/zero/1.0/>.

class Field:
    def __init__(self):
        self._m = [['_','_','_'],['_','_','_'],['_','_','_']]
    def get(self, x, y):
        return self._m[x][y]
    def set(self, x, y, v):
        self._m[x][y] = v
    def __str__(self):
        m = self._m
        return "%c %c %c\n%c %c %c\n%c %c %c" % (
            m[0][0], m[1][0], m[2][0],
            m[0][1], m[1][1], m[2][1],
            m[0][2], m[1][2], m[2][2],
        )
    def dup(self):
        x = []
        for a in self._m:
            y = []
            for b in a:
                y.append(b)
            x.append(y)
        d = Field()
        d._m = x
        return d


field = Field()


def place(field, x, y):
    global cur_player
    global next_player
    if 0 <= x < 3 and 0 <= y < 3 and field.get(x, y) == '_':
        field.set(x, y, cur_player)
        return True
    return False


def check_victory(field, p, x, y):
    if field.get(0, 0) == p and \
        field.get(1, 1) == p and \
        field.get(2, 2) == p:
        return True
    if field.get(0, 2) == p and \
        field.get(1, 1) == p and \
        field.get(2, 0) == p:
        return True
    if field.get(x, 0) == p and \
            field.get(x, 1) == p and \
            field.get(x, 2) == p:
        return True
    if field.get(0, y) == p and \
            field.get(1, y) == p and \
            p == field.get(2, y):
        return True
    return False



def det_best_move():
    for x in [0,1,2]:
        for y in [0,1,2]:
            f = field.dup()
            place(f, x, y)
            if check_victory(f, cur_player, x, y):
                return (x, y)
    for x in [0,1,2]:
        for y in [0,1,2]:
            if place(field.dup(), x, y):
                return (x, y)


cur_player = 'X'
next_player = 'O'

import random
human_player = 'X' if random.randint(0, 1) else 'O'

print('You are', human_player)

while True:
    if cur_player == human_player:
        print()
        print("X: ", end="")
        x = int(input())
        print("Y: ", end="")
        y = int(input())
    else:
        x, y = det_best_move()

    if place(field, x, y):
        print()
        print(field)
        if check_victory(field, cur_player,x, y):
            print()
            print(cur_player, "won!")
            break
        cur_player, next_player = next_player, cur_player
    else:
        print("Invalid input")