checkRO :: BufferM Bool
checkRO = do
  ro <- use readOnlyA
  when ro (fail "Read Only Buffer")
  return ro
checkRO :: BufferM Bool
checkRO = do
  ro <- use readOnlyA
  when ro (fail "Read Only Buffer")
  return ro
checkRO = do
  ro <- use readOnlyA
  when ro (fail "Read Only Buffer")
  return ro