FormatResult = enum
  frNone = 0,               ## No error, format is acceptable
  frInvalidSignature = 1,   ## File has an invalid signature
  frInvalidRevision = 2,    ## File has an unrecognized revision, possibly from a newer version of the format
  frCannotUpgrade = 3,      ## An older revision file could not be upgraded to current revision
  frInvalidSize = 4, ## Attempted to read past the size of a payload block, block data
                      ## is ill-formed
  frInvalidCount = 5,       ## The icount or wcount field in the header is too big
  frInvalidBlock = 6,       ## An invalid/unknown block id was used in a payload block
  frInvalidChannel = 7,     ## An invalid/unknown channel was used in a payload block
  frInvalidSpeed = 8,       ## The format contains an invalid speed, outside of Speed.low..Speed.high
  frInvalidRowCount = 9, ## A TrackFormat's rows field in a SONG block exceeds the Song's
                          ## track size
  frInvalidRowNumber = 10,  ## A RowFormat's rowno field exceeds the Song's track size
  frInvalidId = 11,         ## An instrument or waveform has an invalid id
  frInvalidDuplicateId = 12, ## Two instruments or two waveforms have the same id
  frInvalidTerminator = 13, ## The terminator is invalid.
  frReadError = 14,         ## A read error occurred during processing
  frWriteError = 15          ## A write error occurred during processing

proc deserialize(i: var Instrument; stream: Stream): FormatResult {....raises: [],
    tags: [ReadIOEffect].}

proc deserialize(m: var Module; stream: Stream): FormatResult {....raises: [],
    tags: [ReadIOEffect].}

proc deserialize(s: var Song; stream: Stream): FormatResult {....raises: [],
    tags: [ReadIOEffect].}

proc deserialize(w: var Waveform; stream: Stream): FormatResult {....raises: [],
    tags: [ReadIOEffect].}

proc serialize(i: Instrument; stream: Stream): FormatResult {....raises: [],
    tags: [WriteIOEffect].}

proc serialize(m: Module; stream: Stream): FormatResult {....raises: [],
    tags: [WriteIOEffect].}

proc serialize(s: Song; stream: Stream): FormatResult {....raises: [],
    tags: [WriteIOEffect].}

proc serialize(w: Waveform; stream: Stream): FormatResult {....raises: [],
    tags: [WriteIOEffect].}