Develop Reference

How to add game restart in this pgame code? [duplicate]

This question already has answers here:
how restarting game on pygame works
(1 answer)
Pygame restart function
(2 answers)
In game loop, how do I restart game properly using nested class or loop?
(1 answer)
Reset and restart pygame program doesn't work
(1 answer)
Closed 3 months ago.
I followed a tutorial guide on how to make this game but they never said how to put in a restart. I'm not quite sure how to do it, would anyone here know off the top of their head? Here's the code.
import pygame
import math
import random
from pygame import mixer
# Start the Program
pygame.init()
# Create the Screen
screen = pygame.display.set_mode((800, 600))
running = True
# Background
background = pygame.image.load('background.png')
# Background Sound
mixer.music.load('theme.mp3')
mixer.music.play(-1)
# Title and Icon
pygame.display.set_caption("Boot Craft")
icon = pygame.image.load('Starcraft.png')
pygame.display.set_icon(icon)
# Player
player_image = pygame.image.load('BC.png')
playerX = 370
playerY = 480
playerX_change = 0
playerY_change = 0
# Enemy
enemy_image = []
enemyX = []
enemyY = []
enemyX_change = []
enemyY_change = []
num_of_enemies = 6
for i in range(num_of_enemies):
enemy_image.append(pygame.image.load('Zergling.png'))
enemyX.append(random.randint(0, 768))
enemyY.append(random.randint(50, 150))
enemyX_change.append(0.2)
enemyY_change.append(40)
# Bullet
# Ready - You can't see the bullet on the screen
# Fire - The bullet is currently moving
bullet_image = pygame.image.load('Bullet.png')
bulletX = 0
bulletY = 480
bulletX_change = 0
bulletY_change = .5
bullet_state = "ready"
# Score
score_value = 0
font = pygame.font.Font('freesansbold.ttf', 32)
textX = 10
textY = 10
# Game Over
over_font = pygame.font.Font('freesansbold.ttf', 64)
def show_score(x,y):
score = font.render('Score: ' + str(score_value), True, (255,255,255))
screen.blit(score, (x, y))
def game_over_text():
over_text = over_font.render('GAME OVER', True, (255, 255, 255))
continue_text = over_font.render('CONTINUE? Y/N', True, (255, 255, 255))
screen.blit(over_text, (200, 250))
screen.blit(continue_text, (160, 350))
def player(x, y):
screen.blit(player_image, (x, y))
def enemy(x, y, i):
screen.blit(enemy_image[i], (x, y))
def fire_bullet(x, y):
global bullet_state
bullet_state = "fire"
screen.blit(bullet_image, (x + 8, y + 10))
def isCollision(enemyX, enemyY, bulletX, bulletY):
distance = math.sqrt((math.pow(enemyX - bulletX, 2)) + (math.pow(enemyY - bulletY, 2)))
if distance < 27:
return True
else:
return False
# Game Loop - Runs Game
while running:
# RGB Color Values 0-255
screen.fill((0, 0, 0))
# Background Image
screen.blit(background, (0, 0))
for event in pygame.event.get():
if event.type == pygame.QUIT:
running = False
if event.type == pygame.KEYDOWN:
if event.key == pygame.K_y:
running = True
# Check Key pressed.
if event.type == pygame.KEYDOWN:
if event.key == pygame.K_LEFT or event.key == pygame.K_a:
playerX_change = -0.2
if event.key == pygame.K_RIGHT or event.key == pygame.K_d:
playerX_change = 0.2
if event.key == pygame.K_SPACE:
if bullet_state == "ready":
bullet_sound = mixer.Sound('laser.wav')
bullet_sound.play()
# Get the current X coordinate of the spaceship
bulletX = playerX
fire_bullet(bulletX, bulletY)
# Check Key released.
if event.type == pygame.KEYUP:
if event.key == pygame.K_LEFT or event.key == pygame.K_RIGHT or event.key == pygame.K_a or event.key == pygame.K_d:
playerX_change = 0
playerX += playerX_change
# Adds Boundary
if playerX <= 0:
playerX = 0
elif playerX >= 721:
playerX = 721
# Enemy Movement
for i in range(num_of_enemies):
# Game Over
if enemyY[i] > 440:
for j in range(num_of_enemies):
enemyY[j] = 2000
game_over_text()
enemyX[i] += enemyX_change[i]
if enemyX[i] <= 0:
enemyX_change[i] = 0.2
enemyY[i] += enemyY_change[i]
elif enemyX[i] >= 768:
enemyX_change[i] = -0.2
enemyY[i] += enemyY_change[i]
# Collision
collision = isCollision(enemyX[i],enemyY[i],bulletX,bulletY)
if collision:
explosion_sound = mixer.Sound('explode.wav')
explosion_sound.play()
bulletY = 480
bullet_state = "ready"
score_value += 1
enemyX[i] = random.randint(0, 768)
enemyY[i] = random.randint(50, 150)
enemy(enemyX[i], enemyY[i], i)
# Bullet Movement
if bulletY <= 0:
bulletY = 480
bullet_state = "ready"
if bullet_state == "fire":
fire_bullet(bulletX, bulletY)
bulletY -= bulletY_change
player(playerX, playerY)
show_score(textX, textY)
pygame.display.update()
I'm not sure what to try, as what I googled used different ways of running the game. New to this, so genuinely confused.

How to use time and make a timer in Pygame? [duplicate]

This question already has answers here:
Countdown timer in Pygame
(8 answers)
Spawning multiple instances of the same object concurrently in python
(1 answer)
Closed 5 months ago.
I am new to pygame programming and I am making a game with the help of tutorials. I finished the tutorial and want to add a new feature to my game.
Game Overview
I have created a space invader game where there are enemies moving on the x-axis and slowly coming down. In bottom there is a space ship which can move on the x axis and can shoot bullets to destroy or kill the enemies. The enemies respawn after being killed and if an enemy reaches the bottom, it is game over
Code
# importing modules
import pygame
import random
import math
from pygame import mixer
# initialize pygame
pygame.init()
# creating a window
screen = pygame.display.set_mode((800, 600))
# Background Music
mixer.music.load('background.wav')
mixer.music.play(-1)
# Background
bg_img = pygame.image.load("background3.png")
bg = pygame.transform.scale(bg_img, (800, 600))
# Title and Icon
pygame.display.set_caption("Space Shooters")
icon = pygame.image.load('spaceship.png')
pygame.display.set_icon(icon)
# Player
player = pygame.image.load('spaceship2.png')
playerX = 370
playerY = 500
playerX_change = 0
# Enemy
enemyImg = []
enemyX = []
enemyY = []
enemyX_change = []
enemyY_change = []
num_of_enemies = 6
for i in range(num_of_enemies):
enemyImg.append(pygame.image.load('enemy.png'))
enemyX.append(random.randint(6, 730))
enemyY.append(random.randint(45, 150))
enemyX_change.append(0.3)
enemyY_change.append(40)
# Bullet
# Ready - The bullet can't be seen
# Fire - The bullet has been shot
bulletImg = pygame.image.load('bullet.png')
bulletX = 0
bulletY = 480
bulletX_change = 0
bulletY_change = 1.5
bullet_state = "Ready"
# Score
score_value = 0
font = pygame.font.Font('freesansbold.ttf', 32)
textX = 10
textY = 10
# Game Over
over_font = pygame.font.Font('freesansbold.ttf', 64)
# Function for displaying text
def show_score(x, y):
score = font.render("Score : " + str(score_value), True, (255, 255, 255))
screen.blit(score, (x, y))
def game_over_text():
over_text = over_font.render("GAME OVER", True, (255, 255, 255))
screen.blit(over_text, (200, 250))
# Defining and drawing spaceship
def spaceship(x, y):
screen.blit(player, (x, y))
# Defining and drawing enemy
def enemy(x, y, i):
screen.blit(enemyImg[i], (x, y))
def fire_bullet(x, y):
global bullet_state
bullet_state = "Fire"
screen.blit(bulletImg, (x + 16, y + 10))
def Iscollision(enemyX, enemyY, bulletX, bulletY):
distance = math.sqrt((math.pow(enemyX - bulletX, 2)) + (math.pow(enemyY - bulletY, 2)))
if distance < 27:
return True
else:
return False
# making the game window run endlessly and game loop
running = True
while running:
for event in pygame.event.get():
if event.type == pygame.QUIT:
running = False
# Keystroke check (right, left)
if event.type == pygame.KEYDOWN:
if event.key == pygame.K_LEFT:
playerX_change = -0.3
if event.key == pygame.K_RIGHT:
playerX_change = 0.3
if event.key == pygame.K_SPACE:
# Checking whether bullet is there on screen, if not making it ready, if yes disabling spacebar
if bullet_state == "Ready":
# Get the current X cordinate of spaceship
bulletX = playerX
fire_bullet(bulletX, bulletY)
bullet_sound = mixer.Sound('laser.wav')
bullet_sound.play()
if event.type == pygame.KEYUP:
if event.key == pygame.K_LEFT or event.key == pygame.K_RIGHT:
playerX_change = 0
# Changing X coordinates to move spaceship
playerX += playerX_change
if playerX <= 6:
playerX = 6
elif playerX >= 730:
playerX = 730
screen.fill(0)
screen.blit(bg, (0, 0))
# Enemy Movement
for i in range(num_of_enemies):
# Game Over
if enemyY[i] > 440:
for j in range(num_of_enemies):
enemyY[j] = 2000
game_over_text()
break
for i in range(num_of_enemies):
enemyX[i] += enemyX_change[i]
if enemyX[i] <= 6:
enemyX_change[i] = 0.3
enemyY[i] += enemyY_change[i]
elif enemyX[i] >= 730:
enemyX_change[i] = -0.3
enemyY[i] += enemyY_change[i]
# Collision
collision = Iscollision(enemyX[i], enemyY[i], bulletX, bulletY)
# if collision and if collision is true are both the same
if collision:
collision_sound = mixer.Sound('explosion.wav')
collision_sound.play()
bulletY = 480
bullet_state = "Ready"
score_value += 1
enemyX[i] = random.randint(6, 730)
enemyY[i] = random.randint(45, 150)
enemy(enemyX[i], enemyY[i], i)
# Deleting each frame of enemy moving so that it runs smoothly
# Bullet Movement
if bulletY <= 0:
bulletY = 480
bullet_state = "Ready"
if bullet_state == "Fire":
fire_bullet(bulletX, bulletY)
bulletY -= bulletY_change
spaceship(playerX, playerY)
show_score(textX, textY)
# updating display
pygame.display.update()
New Feature
I want to add a feature that when a laser ( I have a picture) hits the spaceship, shot by the enemies, the spaceship can't move for 10 seconds. I have already tryed other stack overflow questions but they don't match my needs.

If you only have one cooldown to manage, a simple and clean way to do it is by using a custom event :
# Custom event
COOLDOWN_END = pg.USEREVENT
When you detect a collision you simply start a timer :
# Custom event
pg.time.set_timer(COOLDOWN_END, 1000, 1)
The first parameter is the event you are going to send to your event handler, the 2nd is the time in ms (so 1 sec here) and last one is the number of iteration. Here you just want to send the event once, so put 1.
The last step is to do catch this event in your handler and do what you want with it :
for evt in pg.event.get():
if evt.type == pg.QUIT:
exit()
if evt.type == COOLDOWN_END:
print(evt)
# Your logic goes here
Let's put everything together :
(Here, I simply used this technique to have a COOLDOWN_END event 1 sec after I clicked)
# General imports
import pygame as pg
import sys
# Init
pg.init()
# Vars
screen = pg.display.set_mode((500, 500))
pg.display.set_caption("name")
# Clock
FPS = 60
clock = pg.time.Clock()
# Custom event
COOLDOWN_END = pg.USEREVENT
# Main functions
def update():
pass
def draw():
# Clear screen
screen.fill((0,0,0))
def handle_evt():
for evt in pg.event.get():
if evt.type == pg.QUIT:
exit()
if evt.type == pg.KEYDOWN:
if evt.key == pg.K_ESCAPE:
exit()
if evt.type == pg.MOUSEBUTTONDOWN:
if evt.button == 1:
on_click()
if evt.type == COOLDOWN_END:
print(evt)
def on_click():
pg.time.set_timer(COOLDOWN_END, 1000, 1)
def exit():
pg.quit()
sys.exit()
# Main loop
if __name__ == '__main__':
while True:
handle_evt()
update()
draw()
clock.tick(FPS)
pg.display.flip()

You may use custom event with from pygame.locals import USEREVENT.
An alternative is to keep track of time of when you got hit using pygame.time.get_ticks() + some stun cooldown system, and applying only to the portion of the code involved with player movement.
stun_duration = 10000 # milliseconds
damaged_timestamp = -stun_duration # allows to get stunned starting from pygame.init() call
running = True
while running:
for event in pygame.event.get():
# preceding code
# check if beyond stun cooldown
if pygame.time.get_ticks() - damaged_timestamp > stun_duration:
damaged_timestamp = pygame.time.get_ticks()
# Keystroke check (right, left)
if event.type == pygame.KEYDOWN:
if event.key == pygame.K_LEFT:
playerX_change = -0.3
if event.key == pygame.K_RIGHT:
playerX_change = 0.3
if event.key == pygame.K_SPACE:
# Checking whether bullet is there on screen, if not making it ready, if yes disabling spacebar
if bullet_state == "Ready":
# Get the current X cordinate of spaceship
bulletX = playerX
fire_bullet(bulletX, bulletY)
bullet_sound = mixer.Sound('laser.wav')
bullet_sound.play()
if event.type == pygame.KEYUP:
if event.key == pygame.K_LEFT or event.key == pygame.K_RIGHT:
playerX_change = 0
# Changing X coordinates to move spaceship
playerX += playerX_change
if playerX <= 6:
playerX = 6
elif playerX >= 730:
playerX = 730
# proceeding code

Pygame displays a black screen

I did some research to see if I could fix my problem on my own but it has been fruitless so far. I've checked to see if I ran the .display command too much but I haven't, the program will run without error but the screen appears black except when I close the window out, you can catch a glimpse of what it is supposed to display. Any insight into what is wrong? Help is greatly appreciated!
import math
import random
import pygame
from pygame import mixer
# Initialize the pygame
pygame.init()
# create the screen
screen = pygame.display.set_mode((800, 600))
# Background
background = pygame.image.load('space background.png')
# Background Sound
# come back to this from bg music 'mixer.music.load('insert file name')'
# mixer.music.play(-1)
# Title and Icon
pygame.display.set_caption("Space Invaders")
icon = pygame.image.load('ufo.png')
pygame.display.set_icon(icon)
# Player
playerImg = pygame.image.load('ship.png')
playerX = 370
playerY = 480
playerX_change = 0
# Enemy
enemyImg = []
enemyX = []
enemyY = []
enemyX_change = []
enemyY_change = []
num_of_enemies = 6
for i in range(num_of_enemies):
enemyImg.append(pygame.image.load('enemy.png'))
enemyX.append(random.randint(0, 735))
enemyY.append(random.randint(50, 150))
enemyX_change.append(0.3)
enemyY_change.append(40)
# Bullet
# Ready - you cat see the bullet on the screen
# Fire - The bullet is currently moving
bulletImg = pygame.image.load('bullet.png')
bulletX = 0
bulletY = 480
bulletX_change = 0
bulletY_change = 1 # Bullet speed
bullet_state = "ready"
# Score
score_value = 0
font = pygame.font.Font('Minecraft.ttf', 24)
textX = 10
testY = 10 # might have to change back to 'text'
# Game Over text
over_font = pygame.font.Font('Minecraft.ttf', 64)
def show_score(x, y):
score = font.render("Score : " + str(score_value), True, (225, 225, 255))
screen.blit(score, (x, y))
def game_over_text(x, y):
over_text = over_font.render("GAME OVER", True, (225, 225, 255))
screen.blit(over_text, (200, 250))
def player(x, y):
screen.blit(playerImg, (x, y))
def enemy(x, y, i):
screen.blit(enemyImg[i], (x, y))
def fire_bullet(x, y):
global bullet_state
bullet_state = "fire"
screen.blit(bulletImg, (x + 16, y + 10))
def iscollision(enemyX, enemyY, bulletX, bulletY):
distance = math.sqrt(math.pow(enemyX - bulletX, 2)) + (math.pow(enemyY - bulletY, 2))
if distance < 27:
return True
else:
return False
# Game Loop
running = True
while running:
# RGB
screen.fill((0, 0, 0))
# background image
screen.blit(background, (0, 0))
for event in pygame.event.get():
if event.type == pygame.QUIT:
running = False
# if keystroke is pressed check whether its right or left
if event.type == pygame.KEYDOWN:
if event.key == pygame.K_LEFT:
playerX_change = -0.7 # player speed
if event.key == pygame.K_RIGHT:
playerX_change = 0.7
if event.key == pygame.K_SPACE:
if bullet_state == "ready":
bullet_Sound = mixer.Sound('laser.wav')
bullet_Sound.play()
# Get the current X corrdinate of te spaceship
bulletX = playerX
fire_bullet(playerX, bulletY)
if event.type == pygame.KEYUP:
if event.key == pygame.K_LEFT or event.key == pygame.K_RIGHT:
playerX_change = 0
# 5 = 5 + -0.1 -> 5 = 5 - 0.1
# 5 = 5 + 0.1
# Checking for boundries of spaceship
playerX += playerX_change
if playerX <= 0:
playerX = 0
elif playerX >= 736:
playerX = 736
# Enemy Movement
for i in range(num_of_enemies):
# Game over
if enemyY[i] > 440:
for j in range(num_of_enemies):
enemyY[j] = 2000
game_over_text()
break
enemyX[i] += enemyX_change[i]
if enemyX[i] <= 0:
enemyX_change[i] = 0.3 # enemy speed
enemyY[i] += enemyY_change[i]
elif enemyX[i] >= 736:
enemyX_change[i] = -0.3
enemyY[i] += enemyY_change[i]
# Collision
collision = iscollision(enemyX[i], enemyY[i], bulletX, bulletY)
if collision:
explosion_Sound = mixer.Sound('explosion.wav')
explosion_Sound.play()
bulletY = 480
bullet_state = "ready"
score_value += 100
enemyX[i] = random.randint(0, 736)
enemyY[i] = random.randint(50, 150)
enemy(enemyX[i], enemyY[i], i)
# Bullet Movement
if bulletY <= 0:
bulletY = 480
bullet_state = "ready"
if bullet_state == "fire":
fire_bullet(bulletX, bulletY)
bulletY -= bulletY_change
player(playerX, playerY)
show_score(textX, testY)
pygame.display.update()

All you have to do is indent the last bit of code (the 11 lines under the comment Bullet Movement) one level in. Right now, it's not under the while loop, which explains why the screen is black and why it only appears after you click the close button (which exits the loop and executes the drawing code). Hope this helps!

Why does "Game over" text not appear?

I am currently attempting to programm a small game. An enemy is supposed to chase the player, the actual chasing is not implemented yet. I still need to figure out how to do that, but that's not the question.
I have made it so that the player returns to the start point once they collide with the enemy. In addition to that, a text 'Game over' is supposed to appear. The function for that is called at the end of the game loop and while the text appeared briefly(it actually only appeared once, I have tried it multiple times), it does not stay. I was planing on making it appear and then disappear after a few seconds so that the player can play again, but I'm not sure why it disappears instantly.
If this is the wrong place to post this, please tell me, I will delete this post. This is my code, would be amazing if somebody could help me out:
import pygame #imports pygame
import math
pygame.init()
#screen
screen = pygame.display.set_mode((800,600)) #width and height
#title and icon
pygame.display.set_caption("The Great Chase") #changes title
icon = pygame.image.load('game-controller.png')
pygame.display.set_icon(icon) #setting icon
#player
playerImg = pygame.image.load('scary-monster.png')
playerX = 370
playerY = 480
playerX_change = 0
playerY_change = 0
#enemy
enemyImg = pygame.image.load('caterpillar.png')
enemyX = 370
enemyY = 50
enemyX_change = 0
enemyY_change = 0
#GAME OVER
game_over_font = pygame.font.Font('Bubblegum.ttf',64)
def game_over_text():
game_over_text = game_over_font.render("GAME OVER", True, (255, 0, 0))
screen.blit(game_over_text, (200, 250))
def player(x, y): #function for player
screen.blit(playerImg, (x, y)) #draws image of player, blit -> means to draw
def enemy(x, y): #function for enemy
screen.blit(enemyImg,(x,y))
def isCollision(playerX, playerY, enemyX, enemyY):
distance = math.sqrt((math.pow(playerX-enemyX,2)) + (math.pow(playerY - enemyY,2)))
if distance < 25:
return True
else:
return False
def chase():
distance = math.sqrt((math.pow(playerX-enemyX,2)) + (math.pow(playerY - enemyY,2)))
#Game loop
running = True
while running:
screen.fill((255,255,0)) #0-255 RGB-> red, green & blue
for event in pygame.event.get():
if event.type == pygame.QUIT:
running = False
# if keystroke check whether right or left or up or down
if event.type == pygame.KEYDOWN:
if event.key == pygame.K_LEFT:
playerX_change = -0.2
if event.key == pygame.K_RIGHT:
playerX_change = 0.2
if event.key == pygame.K_UP:
playerY_change = -0.2
if event.key == pygame.K_DOWN:
playerY_change = 0.2
if event.type == pygame.KEYUP:
if event.key == pygame.K_LEFT or event.key == pygame.K_RIGHT:
playerX_change = 0
if event.key == pygame.K_UP or event.key == pygame.K_DOWN:
playerY_change = 0
playerX += playerX_change
playerY += playerY_change
#creating borders so that player won't leave screen
if playerX <=0:
playerX = 0
elif playerX >=768:
playerX = 768
if playerY <= 0:
playerY = 0
elif playerY >=568:
playerY = 568
#collision
collision = isCollision(playerX, playerY, enemyX, enemyY)
if collision:
playerY = 480
game_over_text()
player(playerX, playerY)
enemy(enemyX, enemyY)
pygame.display.update()

The collision only occurs for a moment and the game over text is only shown when the object collides. If you want to persist the text, set a gameover variable when the collision is detected and display the text based on the state of the variable:
gameover = False
running = True
while running:
# [...]
collision = isCollision(playerX, playerY, enemyX, enemyY)
if collision:
playerY = 480
gameover = True
player(playerX, playerY)
enemy(enemyX, enemyY)
if gameover:
game_over_text()
pygame.display.update()
Note, collision is set in every frame depending on the position of the objects. However, gameover is set once when a collision occurs and then maintains its state.

Character movement bug in pygame

I made a loop to keep the "enemy" character moving to left and right, but for some reason that I really can't tell why, he just goes to the right and when he hits the border limit that I defined, he "teleports" to the left border and keeps going to the right forever. I even tried to make the "enemyX_change" beeing negative, but he just goes to the left, hit the border and stops. I'm using Python 3.8.
import pygame
import random
# Initiate pygame
pygame.init()
# Display the game window
screen = pygame.display.set_mode((800, 600))
# Title and Icon
pygame.display.set_caption('Space Invaders')
icon = pygame.image.load('icon.png')
pygame.display.set_icon(icon)
# Player
playerSprite = pygame.image.load('player.png')
playerX = 370
playerY = 480
playerX_change = 0
# Enemy
enemySprite = pygame.image.load('enemy.png')
enemyX = random.randint(0, 736)
enemyY = random.randint(50, 150)
enemyX_change = 0.3
enemyY_change = 0
def player(x, y):
screen.blit(playerSprite, (x, y))
def enemy(x, y):
screen.blit(enemySprite, (x, y))
# Game Loop
running = True
while running:
# Background color (RGB)
screen.fill((0, 0, 0))
for event in pygame.event.get():
if event.type == pygame.QUIT:
running = False
# If a key is pressed, check if it's the right or left arrow key
if event.type == pygame.KEYDOWN:
if event.key == pygame.K_LEFT:
playerX_change = -0.3
if event.key == pygame.K_RIGHT:
playerX_change = 0.3
if event.type == pygame.KEYUP:
if event.key == pygame.K_LEFT or event.key == pygame.K_RIGHT:
playerX_change = 0
# Move the spaceship to the left or right
playerX += playerX_change
# Prevents the player from going off the border
if playerX <= 0:
playerX = 0
elif playerX >= 736:
playerX = 736
# Moves the enemy
enemyX += enemyX_change
# Prevents the enemy from going off the border
if enemyX <= 0:
enemyX = 0.3
elif enemyX >= 736:
enemyX = -0.3
player(playerX, playerY)
enemy(enemyX, enemyY)
pygame.display.update()

When the enemy goes out of bounds, then you have to change the movement direction (enemyX_change) rather than the position of the player (enemyX):
enemyX = -0.3
enemyX_change *= -1
Invert enemyX_change when it is less than 0 or greater than the width of the window:
# Moves the enemy
enemyX += enemyX_change
# Prevents the enemy from going off the border
if enemyX <= 0 or enemyX >= 736:
enemyX_change *= -1