code: static public Class<? extends Writable> getSequenceFileOutputValueClass(JobConf conf) { 
      return conf.getClass("mapred.seqbinary.output.value.class", 
                           conf.getOutputValueClass().asSubclass(Writable.class),
                           Writable.class);
    }
docs: Get the value class for the {@link SequenceFile}
  
  @return the value class of the {@link SequenceFile}