nodeNamed ∷ DB → String → IO (Maybe Node)
nodeNamed db name = do
  maybeFile ← fileNodeNamed db name
  if isJust maybeFile
    then return maybeFile
    else tagNodeNamed db name


fileN
nodeNamed ∷ DB → String → IO (Maybe Node)
nodeNamed db name = do
  maybeFile ← fileNodeNamed db name
  if isJust maybeFile
    then return maybeFile
    else tagNodeNamed db name
nodeNamed db name = do
  maybeFile ← fileNodeNamed db name
  if isJust maybeFile
    then return maybeFile
    else tagNodeNamed db name