code: public DColumn getColumn(String storeName, String rowKey, String colName) {
          List<String> colNames = new ArrayList<String>(1);
          colNames.add(colName);
          List<DColumn> columns = getColumns(storeName, rowKey, colNames);
          if(columns.size() == 0) return null;
          else return columns.get(0);
      }
docs: Get a single column for a single row in the given store. If the given row or column
  is not found, null is returned. Otherwise, a {@link DColumn} containing the column
  name and value is returned.
  
  @param storeName Name of store to query.
  @param rowKey    Key of row to read.
  @param colName   Name of column to fetch.
  @return          {@link DColumn} containing the column name and value or null if
  the row or column was not found.