private static Mutation getMutation(Text key, int sum) {
      Column c = new Column();
      c.name = ByteBuffer.wrap(key.toString().getBytes());
      c.value = ByteBuffer.wrap(String.valueOf(sum).getBytes());
      c.timestamp = System.currentTimeMillis() * 1000;

      Mutation m = new Mutation();
      m.column_or_supercolumn = new ColumnOrSuperColumn();
      m.column_or_supercolumn.column = c;
      return m;
    }
    private static Mutation getMutation(String index) {
      Column c = new Column();
      c.name = ByteBuffer.wrap("value".getBytes());
      c.value = ByteBuffer.wrap(index.getBytes());
      c.timestamp = System.currentTimeMillis() * 1000;

      Mutation m = new Mutation();
      m.column_or_supercolumn = new ColumnOrSuperColumn();
      m.column_or_supercolumn.column = c;
      return m;
    }