processRow(row, fields) {
    if (!row) {
      return undefined;
    }

    const processedRow = fields.map(fieldInfo => this.processCell(row, fieldInfo));

    if (!this.opts.includeEmptyRows && processedRow.every(field => field === '')) {
      return undefined;
    }

    return processedRow.join(this.opts.delimiter);
  }
Create the content of a specific CSV row

@param {Object} row JSON object to be converted in a CSV row
@returns {String} CSV string (row)