startUpdateTransactionB :: BufferM ()
startUpdateTransactionB = do
  transactionPresent <- use updateTransactionInFlightA
  if transactionPresent
  then error "Already started update transaction"
  else do
    undosA %= addChangeU InteractivePoint
    assign updateTransactionInFlightA True
startUpdateTransactionB :: BufferM ()
startUpdateTransactionB = do
  transactionPresent <- use updateTransactionInFlightA
  if transactionPresent
  then error "Already started update transaction"
  else do
    undosA %= addChangeU InteractivePoint
    assign updateTransactionInFlightA True
startUpdateTransactionB = do
  transactionPresent <- use updateTransactionInFlightA
  if transactionPresent
  then error "Already started update transaction"
  else do
    undosA %= addChangeU InteractivePoint
    assign updateTransactionInFlightA True