# File lib/zombies.rb, line 98
  def draw
    if $DEBUG then
      c = Gosu::Color::DK_GRAY
      (0..W).step(U) do |x|
        draw_line x, 0, c, x, H, c
      end
      (0..H).step(U) do |y|
        draw_line 0, y, c, W, y, c
      end
    end
    people.each do |person|
      person.draw
    end
  end