code: public Table sampleN(int nRows) {
          Preconditions.checkArgument(nRows > 0 && nRows < rowCount(),
                  "The number of rows sampled must be greater than 0 and less than the number of rows in the table.");
          return where(selectNRowsAtRandom(nRows, rowCount()));
      }
docs: Returns a table consisting of randomly selected records from this table
  
  @param nRows The number of rows to go in the sample