sprites.py

def collide_with_walls(self, dir):
        if dir == 'x':
            hits = pg.sprite.spritecollide(self, self.game.walls, False, collide_collision_rect)
            if hits:
                if self.vel.x > 0:
                    self.pos.x = hits[0].rect.left - self.rect.width
                if self.vel.x < 0:
                    self.pos.x = hits[0].rect.right
                self.vel.x = 0
                self.rect.x = self.pos.x
        if dir == 'y':
            hits = pg.sprite.spritecollide(self, self.game.walls, False, collide_collision_rect)
            if hits:
                if self.vel.y > 0:
                    self.pos.y = hits[0].rect.top - self.rect.height
                if self.vel.y < 0:
                    self.pos.y = hits[0].rect.bottom
                self.vel.y = 0
                self.rect.y = self.pos.y