* @param {String} fieldName - The name of the field for the group to return
 * @returns String - The specified value
 * @example {{ files | byPlatform | categorize(branch.diff.files_metadata) | readField('jvm', 'name') }}
 */

function readField(objects, objectName, fieldName) {
    let group = Object.values(objects).find(s => s.name === objectName);
    if (group) {
        const result = group[fieldName];
        if (result === undefined) {

/**
 * @module byPlatform
 * @description Groups the PR's files by platform based on the file's path.
 * @param {string[]} files - the gitStream's files context variable
 * @returns {Map} - Map from platform to list of files in this PR in it
 * @example {{ owners | byPlatform }}
 */
function byPlatform(files) {
    const result = new Map();
    files.forEach(file => {
        const platform = getPlatform(file);
        if (!result.has(platform)) {

/**
 * @module byCodeowner
 * @description Groups the PR's files' by owner based on the CODEOWNERs file.
 * @param {string[]} files - the gitStream's files context variable
 * @param {Object} pr - the gitStream's pr context variable
 * @param {string} token - access token with repo:read scope, used to read the CODEOWNERS file
 * @param {string} pathToCodeOwners - path from repo root to CODEOWNERS file
 * @returns {Map} - Map from owner name to list of files they own

  const rollback_commit = context.payload.head_commit.id;
  const pr_match_groups = context.payload.head_commit.message.match(/\Rollback of PR #(\d+).*/) || [];
  if (pr_match_groups.length != 2) {
    console.log(`PR Number not found in ${context.payload.head_commit.message}`);
    throw "Error extracting PR Number from commit message";
  }
  const pr_number = parseInt(pr_match_groups[1]);
  const owner = context.payload.repository.owner.name;

 *
 * @param {[Object]} statistics - list of summary data objects from computeStatistics
 * @param {String} title - description of how data is grouped
 * @returns {String} Returns the formatted HTMl table string.
 * @example {{ owners | categorize(branch.diff.files_metadata) | computeStatistics(branch.diff.files_metadata) | summaryTable('Platform') }}
 */