text: Yo, check it,
  Back in '79, O'Brien and Fleming,
  They dropped a procedure, clinical trials be the thing.
  For acute disease, they had a plan,
  But we took their method, flipped it for chronic, man.
  
  No need for modifications, it's all good,
  Type I errors unchanged, power understood.
  Compared to single-sample, no loss in sight,
  Their procedure holds up, shining bright.
  
  But hold up, chronic models, they're a bit different,
  Savings in sample size, not as magnificent.
  Still, we found a way, let me break it down,
  Predicting reduction in size, straight from the power's crown.
  
  So remember, for any disease model you see,
  With a fixed inspection limit, listen to me,
  You can easily predict the sample size drop,
  Based on the power, no need to stop.