code: function getColumnValueAsString(columnIdentifier)
    {
      // resolve the column identifier to the correct column if possible
      var column = resolveColumnIdentifierToColumn(
          columns, columnIdentifier, mapColumnNameToIndices);
  
      return column ? column.getRowValueAsString(this) : undefined;
    }
docs: Returns the value of a column as a String.
  
  @param {String | Number} columnIdentifier this can be either the column
  name or the column index.
  
  @returns {*}