internal
fetchInstrumentDef :: Instrument -> InstrumentDef
fetchInstrumentDef (StdInstrument x)   = Data.Maybe.fromMaybe (error "Bad instr") $ Data.getInstrumentDefByGeneralMidiProgram (x + 1)
fe
fetchInstrumentDef :: Instrument -> InstrumentDef
fetchInstrumentDef (StdInstrument x)   = Data.Maybe.fromMaybe (error "Bad instr") $ Data.getInstrumentDefByGeneralMidiProgram (x + 1)
fetchInstrumentDef (StdInstrument x)   = Data.Maybe.fromMaybe (error "Bad instr") $ Data.getInstrumentDefByGeneralMidiProgram (x + 1)