code: @Override
  	public void prepare() throws Exception {
  		TaskConfig config = this.taskContext.getTaskConfig();
  		if (config.getDriverStrategy() != DriverStrategy.SORTED_GROUP_REDUCE) {
  			throw new Exception("Unrecognized driver strategy for GroupReduce driver: " + config.getDriverStrategy().name());
  		}
  		this.serializer = this.taskContext.<IT>getInputSerializer(0).getSerializer();
  		this.comparator = this.taskContext.getInputComparator(0);
  		this.input = this.taskContext.getInput(0);
  	}
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