Now you can't possibly test a medicine on ten thousand people before you start to sell it, so that sort of risk, as rare a risk as that, will only be picked up when the medicine has actually been in use and on the market and been properly prescribed for some years, and what we are doing now, and what is particularly interesting, is to start to use computers to pick up these adverse reactions so that we know much more quickly in future if a medicine is doing any harm and we can either stop prescribing it for the people who are going to suffer from it, and that's the most likely thing, or else take it off the market altogether if it's  if we don't  if we can't pick out the people who might be at risk.