python - Stuck in a stupid phase of coding game of life -

i've been trying code game of life own want learn python , thought practice , have finish except need pass variable method dont know how know seem dumb wait bit , see code not easy sound unless me

import random,time f=3 c=3 contador = 0 tablero = [] tablero_dibujado = []  class juego(object):      def tablero(self): #create board         in range(f):             tablero.append([0]*c)             tablero_dibujado.append([0]*c)      def rellenar_tablero_random(self): #fill board random 0 , 1         in range(f):             j in range(c):                 tablero[i][j] = random.randint(0,1)         print(tablero)      def rellenar_tablero_manual(self): #just fill board manually if want reason         tablero[0][1] = 1         in range(2):             tablero[1][i] = 1         print(tablero)      def distancia_vecino(self,cell_f,cell_c):   #measure distance possible neighbours         distancia_vecino = [(-1,-1),(-1,0),(-1,1),(0,1),(1,1),(1,0),(1,-1),(0,-1)]         in range(8):             string = distancia_vecino[i]             comparar_string = str(string)             x,y = comparar_string.split(",")             x = str(x).replace(",","")             y = str(y).replace(",","")             x = x.replace("(","")             y = y.replace(")","")             y = y.replace(" ","")             x = int(x) + cell_f             y = int(y) + cell_c              if x>=f or x<0:                 continue             else:                 if y>=c or y<0:                     continue                 else:                     game.detectar_vecino(cell_f,cell_c,x,y)         game.vida(cell_f,cell_c)      def detectar_vecino(self, cell_f, cell_c, x, y):    #check how many neighboards have         vecinos = 0          if tablero[cell_f][cell_c] == 1:             if tablero[cell_f][cell_c] == tablero[x][y]:                 vecinos+=1         else:             if tablero[cell_f][cell_c] != tablero[x][y]:                 vecinos+=1         contador = contador + vecinos      def iterar_tablero(self): #just iterate board check values         in range(f):             j in range(c):                 game.distancia_vecino(i,j)         = input() #in order screen dont close after executing      def vida(self, cell_f, cell_c): #check if alive , if should alive or dead          print(contador)         if tablero[cell_f][cell_c] == 1:             if contador > 3 or contador < 2:                 tablero[cell_f][cell_c] = 0         else:             if contador == 3:                 tablero[cell_f][cell_c] = 1          game.dibujar_tablero()      def dibujar_tablero(self): #draw board in more way         contador1 = 0         in range(f):             j in range(c):                 if tablero[i][j] == 1:                      tablero_dibujado[i][j] = "§"                 else:                      tablero_dibujado[i][j] = "■"          in tablero_dibujado:             print(" ")             j in i:                 print(j, end=" ")         print("")         time.sleep(2)   game = juego() game.tablero() game.rellenar_tablero_manual() game.iterar_tablero() 

what need in detectar_vecino have neighbour of cell in board , problem doing got : local variable 'contador' referenced before assignment. , know why happen.however couldnt find alternative way of doing please if know how can solve it.

i want clarify isnt work anywhere,im doing own hobby , want finish thank time appreciate it

add line global contador below

def detectar_vecino(self, cell_f, cell_c, x, y):     global contador   # add line.     vecinos = 0      if tablero[cell_f][cell_c] == 1:         if tablero[cell_f][cell_c] == tablero[x][y]:             vecinos+=1     else:         if tablero[cell_f][cell_c] != tablero[x][y]:             vecinos+=1     contador = contador + vecinos