Task: Conway's Game of Life
Java: public class GameOfLife{
	public static void main(String[] args){
		String[] dish= {
				"_#_",
				"_#_",
				"_#_",};
		int gens= 3;
		for(int i= 0;i < gens;i++){
			System.out.println("Generation " + i + ":");
			print(dish);
			dish= life(dish);
		}
	}

	public static String[] life(String[] dish){
		String[] newGen= new String[dish.length];
		for(int row= 0;row < dish.length;row++){
			newGen[row]= "";
			for(int i= 0;i < dish[row].length();i++){
				String above= "";
				String same= "";
				String below= "";
				if(i == 0){
					
					
					above= (row == 0) ? null : dish[row - 1].substring(i,
									i + 2);
					same= dish[row].substring(i + 1, i + 2);
					
					
					below= (row == dish.length - 1) ? null : dish[row + 1]
									.substring(i, i + 2);
				}else if(i == dish[row].length() - 1){
					
					
					above= (row == 0) ? null : dish[row - 1].substring(i - 1,
									i + 1);
					same= dish[row].substring(i - 1, i);
					
					
					below= (row == dish.length - 1) ? null : dish[row + 1]
									.substring(i - 1, i + 1);
				}else{
					
					
					above= (row == 0) ? null : dish[row - 1].substring(i - 1,
									i + 2);
					same= dish[row].substring(i - 1, i)
									+ dish[row].substring(i + 1, i + 2);
					
					
					below= (row == dish.length - 1) ? null : dish[row + 1]
									.substring(i - 1, i + 2);
				}
				int neighbors= getNeighbors(above, same, below);
				if(neighbors < 2 || neighbors > 3){
					newGen[row]+= "_";
				}else if(neighbors == 3){
					newGen[row]+= "#";
				}else{
					newGen[row]+= dish[row].charAt(i);
				}
			}
		}
		return newGen;
	}

	public static int getNeighbors(String above, String same, String below){
		int ans= 0;
		if(above != null){
			for(char x: above.toCharArray()){
				if(x == '#') ans++;
			}
		}
		for(char x: same.toCharArray()){
			if(x == '#') ans++;
		}
		if(below != null){
			for(char x: below.toCharArray()){
				if(x == '#') ans++;
			}
		}
		return ans;
	}

	public static void print(String[] dish){
		for(String s: dish){
			System.out.println(s);
		}
	}
}

Python: cell_size = 10
sample = 10 
play = False   
last_cell = 0

def setup():
    global grid, next_grid, rows, cols
    size(800, 500)

    rows = height / cell_size
    cols = width / cell_size
    grid = empty_grid()
    next_grid = empty_grid()
    randomize_grid()

    println("Press 'space' to start/stop")
    println("'e' to clear all cells")
    println("'b' demonstrate 'blinker'")
    println("'g' demonstrate glider")
    println("'r' to randomize grid")
    println("'+' and '-' to change speed")

def draw():
    background(0)
    for i in range(cols):
        x = i * cell_size
        for j in range(rows):
            y = j * cell_size
            current_state = grid[i][j]
            fill(255)
            noStroke()
            if current_state:
                rect(x, y, cell_size, cell_size)
            if play:
                ngbs_alive = calc_ngbs_alive(i, j)
                result = rule(current_state, ngbs_alive)
                next_grid[i][j] = result
                
    if play and frameCount % sample == 0 and not mousePressed:
        step()

def rule(current, ngbs):
    
    if ngbs < 2 or ngbs > 3:
        return 0  
    elif ngbs == 3:
        return 1  
    else:
        return current  

def calc_ngbs_alive(i, j):
    NEIGHBOURS = ((-1, 00), (01, 00),  
                  (-1, -1), (00, -1),
                  (01, -1), (-1, 01),
                  (00, 01), (01, 01))
    alive = 0
    for iv, jv in NEIGHBOURS:
        alive += grid[(i + iv) % cols][(j + jv) % rows]
    return alive

def empty_grid():
    grid = []
    for _ in range(cols):
        grid.append([0] * rows)
    return grid

def randomize_grid():
    from random import choice
    for i in range(cols):
        for j in range(rows):
            grid[i][j] = choice((0, 1))

def step():
    global grid, next_grid
    grid = next_grid
    next_grid = empty_grid()

def keyReleased():
    global grid, play, sample
    if key == "e":
        grid = empty_grid()
    if key == "r":
        randomize_grid()
    if key == "g":
         grid[10][10:13] = [0, 1, 0]       
         grid[11][10:13] = [0, 0, 1]       
         grid[12][10:13] = [1, 1, 1]       
    if key == "b":
         grid[10][10:13] = [0, 1, 0]       
         grid[11][10:13] = [0, 1, 0]       
         grid[12][10:13] = [0, 1, 0]               
    if key == " ":
        play = not play 
    if  str(key) in '+=':
        sample = max(sample - 1, 1);
    if key == '-':
        sample += 1

def mousePressed():
    paint()
    
def mouseDragged():
    paint()

def paint():
    global last_cell
    i, j = mouseX // cell_size, mouseY // cell_size
    p = j * cols + i
    if p != last_cell:
        last_cell = p
        grid[i][j] = (1, 0)[grid[i][j]]