NameError: name 'o' is not defined

[Algabri]

fig = plt.figure(figsize=(16,16))
plt.scatter(xt,yt, s=20, label='State', c='k')
plt.scatter(xt[0],yt[0], s=100, label='Start', c='g')
plt.scatter(xt[-1],yt[-1], s=100, label='Goal', c='r')
plt.scatter(o[0][0],o[0][1], s=100, label='Start', c='y')
plt.scatter(o[-1][0] ,o[-1][1], s=100, label='Goal', c='r')
for i in range (len(o)):
plt.scatter(o[i][0],o[i][1], s=20, label='State', c='b')

plt.xlabel('X')
plt.ylabel('Y')
plt.title('Position')
plt.legend(loc='best')
plt.axis('equal')