I was just going to say, to answer your initial question, that it depends on how long you think the price change is going to be for. If you think it's a short-term phenomenon, then the reaction will be somewhat different from what it would be if you think it's going to be a longer-term phenomenon. If you think the price is going to be $50 to $60 for a long period of time, that will change the reaction for many things.
It is true that shale can start or stop more quickly. In fact, what has happened is that the shale plays have drilled their wells and have not completed them, because two-thirds of their cost is in completion. If you believe prices are going to go up, you may as well wait six months, spend one-third, and.... What some people don't understand about shale is that half of your shale production occurs in the first three years, so if you believe prices are going to go up and half of your production is done in three years, you may as well wait for the price to go up.
But it comes down to how you react to price falls. It depends on whether you believe it to be a short-term, a medium-term or a longer-term phenomenon. If it's a longer-term phenomenon, many of the projects that might go forward—not currently operating but that might go forward in the future—won't go forward.