Making Pygame platformer camera scroll vertically?

Question

I'm creating a platformer on pygame based on a YouTube tutorial, but I don't know how to make the camera scroll vertically. I think I have to connect world_shift with player, but I dont know how. When I tried to run the program world_shift_y did not work.

import pygame 
from support import import_csv_layout, import_cut_graphics
from settings import tile_size, screen_height, screen_width
from tiles import *
from player import Player

class Level:
    def __init__(self,level_data,surface):
        self.display_surface = surface
        self.world_shift = 0
        self.world_shift_height = 0
        self.current_x = None

        player_layout = import_csv_layout(level_data['player'])
        self.player = pygame.sprite.GroupSingle()
        self.player_setup(player_layout)

        self.dust_sprite = pygame.sprite.GroupSingle()
        self.player_on_ground = False

        terrain_layout = import_csv_layout(level_data['terrain'])
        self.terrain_sprites = self.create_tile_group(terrain_layout,'terrain')

    def create_tile_group(self,layout,type):
        sprite_group = pygame.sprite.Group()

        for row_index, row in enumerate(layout):
            for col_index,val in enumerate(row):
                if val != '-1':
                    x = col_index * tile_size
                    y = row_index * tile_size

                    if type == 'terrain':
                        sprite = Tile(tile_size, x, y)
                        sprite_group.add(sprite)
        
        return sprite_group

    def player_setup(self,layout):
        for row_index, row in enumerate(layout):
            for col_index,val in enumerate(row):
                x = col_index * tile_size
                y = row_index * tile_size
                if val == '0':
                    sprite = Player((x,y),self.display_surface,self.create_jump_particles)
                    self.player.add(sprite)

    def horizontal_movement_collision(self):
        player = self.player.sprite
        player.rect.x += player.direction.x * player.speed
        collidable_sprites = self.terrain_sprites.sprites()
        for sprite in collidable_sprites:
            if sprite.rect.colliderect(player.rect):
                if player.direction.x < 0: 
                    player.rect.left = sprite.rect.right
                    player.on_left = True
                    self.current_x = player.rect.left
                elif player.direction.x > 0:
                    player.rect.right = sprite.rect.left
                    player.on_right = True
                    self.current_x = player.rect.right

        if player.on_left and (player.rect.left < self.current_x or player.direction.x >= 0):
            player.on_left = False
        if player.on_right and (player.rect.right > self.current_x or player.direction.x <= 0):
            player.on_right = False

    def vertical_movement_collision(self):
        player = self.player.sprite
        player.apply_gravity()
        collidable_sprites = self.terrain_sprites.sprites()

        for sprite in collidable_sprites:
            if sprite.rect.colliderect(player.rect):
                if player.direction.y > 0: 
                    player.rect.bottom = sprite.rect.top
                    player.direction.y = 0
                    player.on_ground = True
                elif player.direction.y < 0:
                    player.rect.top = sprite.rect.bottom
                    player.direction.y = 0
                    player.on_ceiling = True

        if player.on_ground and player.direction.y < 0 or player.direction.y > 1:
            player.on_ground = False
        if player.on_ceiling and player.direction.y > 0.1:
            player.on_ceiling = False

    def scroll_x(self):
        player = self.player.sprite
        player_x = player.rect.centerx
        direction_x = player.direction.x

        if player_x < screen_width / 4 and direction_x < 0:
            self.world_shift = 6
            player.speed = 0
        elif player_x > screen_width - (screen_width / 4) and direction_x > 0:
            self.world_shift = -6
            player.speed = 0
        else:
            self.world_shift = 0
            player.speed = 6

    def scroll_y(self):
        player = self.player.sprite
        player_y = player.rect.centery
        direction_y = player.direction.y

        if player_y < screen_height / 6 and direction_y < 0:
            self.world_shift_height = -20
            player.jump_speed = 0
        elif player_y > screen_height - (screen_height / 6) and direction_y > 0:
            self.world_shift_height = 20
            player.jump_speed = 0
        else:
            self.world_shift_height = 0
            player.jump_speed = -20

    def get_player_on_ground(self):
        if self.player.sprite.on_ground:
            self.player_on_ground = True
        else:
            self.player_on_ground = False

    def run(self):
        self.terrain_sprites.update(self.world_shift)
        self.terrain_sprites.update(self.world_shift_height)
        self.terrain_sprites.draw(self.display_surface)

        self.player.update()
        self.horizontal_movement_collision()    
        self.get_player_on_ground()
        self.vertical_movement_collision()
        self.create_landing_dust()      
        self.scroll_x()
        self.player.draw(self.display_surface)