anchor.diff:  
   let fileIO = io {
       let! lines = File.readLines fName // sequence of io actions which each read a line from a file
  -    let! floatLines = IO.traverseM (IO.map float) lines // parse each line, collecting the results
  -    do! IO.traverseM_ (Console.printfn "%f") floatLines // print each float to the console
  +    let! floatLines = IO.mapM (IO.map float) lines // parse each line, collecting the results
  +    do! IO.iterM (Console.printfn "%f") floatLines // print each float to the console
   }
   
   try
  
positive.code:     let! l1 = Console.readLine
      let! l2 = Console.readLine
      let! l3 = Console.readLine
      do! Console.printf "You entered: %A" [l1; l2; l3]
  } |> IO.run
  
  (**
  
negative.code: 
  *)
  
  let exmpl2 = io {return! Console.readLine}
  printfn "%s" (IO.run exmpl2)
  printfn "%s" (IO.run exmpl2)
  
  (**
  
  