The background star field

StarField.py

class StarField():
  def __init__(self):
    self.star_field_slow = self.create_stars(50)
    self.star_field_medium = self.create_stars(35)
    self.star_field_fast = self.create_stars(30)

  def create_stars(self, number_of_stars):
    stars = []
    for _ in range(number_of_stars):
      star_loc_x = random.randrange(0, constants.SCREEN_WIDTH)
      star_loc_y = random.randrange(0, constants.SCREEN_HEIGHT)
      stars.append([star_loc_x, star_loc_y])
    return stars

  def render_stars(self, screen, star_collection, speed, size, color):
    for star in star_collection:
      star[1] += speed
      if star[1] > constants.SCREEN_HEIGHT:
        star[0] = random.randrange(0, constants.SCREEN_WIDTH)
        star[1] = random.randrange(-20, -5)
      pygame.draw.circle(screen, color, star, size)

  def render(self, screen):
    self.render_stars(screen, self.star_field_slow, 1, 3, DARKGREY)
    self.render_stars(screen, self.star_field_medium, 4, 2, LIGHTGREY)
    self.render_stars(screen, self.star_field_fast, 8, 1, YELLOW)