func NewLevel(game *Game, size Size) *Level {
	level := &Level{}
	level.game = game
	level.size = size
	level.lastUpdate = time.Now()
	level.snake = NewSnake(Position{level.size.Width / 2, level.size.Height / 2}, Direction{0, 1})
	level.apple = &Apple{level.GetRandomPosition()}
	return level
}
NewLevel creates a new level of a certain size,
also spawning in the snake and an apple
package snake
import (
	"math/rand"
	"time"
)
const updateIntervalMs = 100
type Level struct {
	game *Game
	size Size
	lastUpdate time.Time
	snake *Snake
	apple *Apple
}