def do(actor, targets)
    return if targets.empty?
    #Apply thrust to the creature's movement vector, adjusted by elapsed time.
    actor.vector += Vector.new(
      delta,
      Utility.find_angle(actor.location, random_target(targets).location)
    )
  end
def do(actor, targets)
    return if targets.empty?
    #Apply thrust to the creature's movement vector, adjusted by elapsed time.
    actor.vector += Vector.new(
      delta,
      Utility.find_angle(actor.location, random_target(targets).location)
    )
  end
Accelerate toward the first target, but limited by rate.