code: public Rule AbcFile() {
  		//return ZeroOrMore(FirstOfS(AbcTune(), Comment(), Xcommand(),
  		//		FileField(), TextLine(), Tex())).label("AbcFile");
  		return Sequence(
  			ZeroOrMore(
  				FirstOfS(Eols(),
  					Comment(), Xcommand(), Tex(),
  					FileField(), TextLine() 
  				)).label(AbcTuneBookHeader),
  			AbcTune(),
  			ZeroOrMoreS(
  				//SequenceS(
  				//	ZeroOrMoreS(Comment()),
  				//	OptionalS(Eols()),
  					//FirstOf(EOI, AbcTune())
  					AbcTune()
  				//)
  			)
  		).label(AbcFile);
  	}
docs: abc-file ::= *(abc-tune / comment / xcommand / file-field / text-line /
  tex)