if len(os.Args) < 2 {
		usage("missing command selector")
	}

	// Select mode
	var op covOperation
	cmd := os.Args[1]
	switch cmd {
	case mergeMode:
		op = makeMergeOp()
	case debugDumpMode:
		op = makeDumpOp(debugDumpMode)
	case textfmtMode:
		op = makeDumpOp(textfmtMode)
	case percentMode:
		op = makeDumpOp(percentMode)
	case funcMode:
		op = makeDumpOp(funcMode)