code: protected Locator byRowColumn(int rowIndex, int colIndex) {
          if (rowIndex < 1) {
              throw new IllegalArgumentException("Row index must be greater than 0.");
          }
  
          if (colIndex < 1) {
              throw new IllegalArgumentException("Column index must be greater than 0.");
          }
  
          String xpath = bodyTag.isPresent()
                  ? "./tbody/tr[" + rowIndex + "]/td[" + colIndex + "]"
                  : "./tr[" + rowIndex + "]/td[" + colIndex + "]";
  
          return byInner(By.xpath(xpath));
      }
docs: Conveniently allows column implementations to lookup cells inside a column without
  duplicating the effort to come up with xpath for each column's cells. Simply use this method
  with that column's index.
  
  @return A locator that finds a cell based on a row and column index. It does this by
  constructing an xpath. If a {@code<tbody>} tag is present, this will use,
  "./tbody/tr[rowIndex]/td[colIndex]". If no {@code<tbody>} tag is present,
  "./tr[rowIndex]/td[colIndex]" will be used.
  
  <p>If your modelling an unconventionally structured html table, you're encouraged to override
  this method.
  
  @param rowIndex Starting from the top, at 1.
  @param colIndex Starting from the left, at 1.