As an expert Python developer, reflect on the following code and its output. Identify any issues or potential improvements. Then, provide an improved version of the code.

Original Code:
```python
([['<br/>You are an expert Python developer. Based on the following task description, generate clean, well-documented, and functional code.<br/><br/>Task Description:<br/>write a snake game<br/><br/>Instructions:<br/>- Provide only the necessary code without additional explanations.<br/>- Enclose the code within markdown code blocks specifying the language.<br/>- Ensure the code follows best practices and coding standards.<br/>- Include comments where necessary for clarity.<br/>', '<pre><code class="`python"><br/>import pygame<br/>import sys<br/>import time<br/>import random<br/><br/># Initialize Pygame<br/>pygame.init()<br/><br/># Set up display<br/>CELL_SIZE = 20<br/>CELL_NUMBER = 30<br/>SCREEN_WIDTH = CELL_SIZE * CELL_NUMBER<br/>SCREEN_HEIGHT = CELL_SIZE * CELL_NUMBER<br/>screen = pygame.display.set_mode((SCREEN_WIDTH, SCREEN_HEIGHT))<br/>pygame.display.set_caption(\'Snake Game\')<br/><br/># Set up game clock<br/>clock = pygame.time.Clock()<br/><br/># Define colors<br/>RED = pygame.Color(\'red\')<br/>GREEN = pygame.Color(\'green\')<br/>BLACK = pygame.Color(\'black\')<br/>WHITE = pygame.Color(\'white\')<br/><br/># Set up font<br/>font = pygame.font.SysFont(\'arial\', 25)<br/><br/>def show_score(score):<br/>    """Display the current score on the screen."""<br/>    score_surface = font.render(f\'Score: {score}\', True, WHITE)<br/>    score_rect = score_surface.get_rect()<br/>    screen.blit(score_surface, score_rect)<br/><br/>def game_over(score):<br/>    """Handle game over state."""<br/>    game_over_font = pygame.font.SysFont(\'arial\', 50)<br/>    game_over_surface = game_over_font.render(\'Game Over\', True, RED)<br/>    game_over_rect = game_over_surface.get_rect(center=(SCREEN_WIDTH / 2, SCREEN_HEIGHT / 2))<br/>    screen.blit(game_over_surface, game_over_rect)<br/>    pygame.display.flip()<br/>    time.sleep(2)<br/>    pygame.quit()<br/>    sys.exit()<br/><br/>def main():<br/>    # Initial snake position and body<br/>    snake_pos = [SCREEN_WIDTH // 2, SCREEN_HEIGHT // 2]<br/>    snake_body = [list(snake_pos), [snake_pos[0] - CELL_SIZE, snake_pos[1]], [snake_pos[0] - (2 * CELL_SIZE), snake_pos[1]]]<br/>    direction = \'RIGHT\'<br/>    change_to = direction<br/><br/>    # Initial food position<br/>    food_pos = [random.randrange(1, CELL_NUMBER) * CELL_SIZE, random.randrange(1, CELL_NUMBER) * CELL_SIZE]<br/>    food_spawn = True<br/><br/>    # Initial score<br/>    score = 0<br/><br/>    while True:<br/>        # Event handling<br/>        for event in pygame.event.get():<br/>            if event.type == pygame.QUIT:<br/>                pygame.quit()<br/>                sys.exit()<br/>            # Key press events<br/>            elif event.type == pygame.KEYDOWN:<br/>                if event.key in (pygame.K_UP, pygame.K_w) and direction != \'DOWN\':<br/>                    change_to = \'UP\'<br/>                elif event.key in (pygame.K_DOWN, pygame.K_s) and direction != \'UP\':<br/>                    change_to = \'DOWN\'<br/>                elif event.key in (pygame.K_LEFT, pygame.K_a) and direction != \'RIGHT\':<br/>                    change_to = \'LEFT\'<br/>                elif event.key in (pygame.K_RIGHT, pygame.K_d) and direction != \'LEFT\':<br/>                    change_to = \'RIGHT\'<br/>                elif event.key == pygame.K_ESCAPE:<br/>                    pygame.quit()<br/>                    sys.exit()<br/><br/>        # Validate direction change<br/>        if change_to == \'UP\' and direction != \'DOWN\':<br/>            direction = \'UP\'<br/>        elif change_to == \'DOWN\' and direction != \'UP\':<br/>            direction = \'DOWN\'<br/>        elif change_to == \'LEFT\' and direction != \'RIGHT\':<br/>            direction = \'LEFT\'<br/>        elif change_to == \'RIGHT\' and direction != \'LEFT\':<br/>            direction = \'RIGHT\'<br/><br/>        # Move the snake<br/>        if direction == \'UP\':<br/>            snake_pos[1] -= CELL_SIZE<br/>        elif direction == \'DOWN\':<br/>            snake_pos[1] += CELL_SIZE<br/>        elif direction == \'LEFT\':<br/>            snake_pos[0] -= CELL_SIZE<br/>        elif direction == \'RIGHT\':<br/>            snake_pos[0] += CELL_SIZE<br/><br/>        # Snake body growing mechanism<br/>        snake_body.insert(0, list(snake_pos))<br/>        if snake_pos == food_pos:<br/>            score += 1<br/>            food_spawn = False<br/>        else:<br/>            snake_body.pop()<br/><br/>        # Spawn new food<br/>        if not food_spawn:<br/>            food_pos = [random.randrange(1, CELL_NUMBER) * CELL_SIZE, random.randrange(1, CELL_NUMBER) * CELL_SIZE]<br/>            food_spawn = True<br/><br/>        # Clear screen<br/>        screen.fill(BLACK)<br/><br/>        # Draw snake<br/>        for block in snake_body:<br/>            pygame.draw.rect(screen, GREEN, pygame.Rect(block[0], block[1], CELL_SIZE, CELL_SIZE))<br/><br/>        # Draw food<br/>        pygame.draw.rect(screen, RED, pygame.Rect(food_pos[0], food_pos[1], CELL_SIZE, CELL_SIZE))<br/><br/>        # Check for collisions with boundaries<br/>        if (snake_pos[0] &lt; 0 or snake_pos[0] &gt;= SCREEN_WIDTH or<br/>            snake_pos[1] &lt; 0 or snake_pos[1] &gt;= SCREEN_HEIGHT):<br/>            game_over(score)<br/><br/>        # Check for collisions with itself<br/>        if snake_pos in snake_body[1:]:<br/>            game_over(score)<br/><br/>        # Display score<br/>        show_score(score)<br/><br/>        # Refresh game screen<br/>        pygame.display.update()<br/><br/>        # Set game speed<br/>        clock.tick(15)<br/><br/>if __name__ == \'__main__\':<br/>    main()</code></pre>']], 1, '<Response [200]>', {'interactive': True, '__type__': 'update'})
```

Execution Output:


Instructions:
- Analyze the code and its output.
- Identify any errors, inefficiencies, or areas for improvement.
- Provide an improved version of the code within markdown code blocks.
- Include a brief explanation of the changes made.