function insertPlaceholderIdentifiers(sourceLiterals) {
  let source = sourceLiterals[0];
  for (let i = 1; i < sourceLiterals.length; i++) {
    source += PREFIX + String(i - 1) + sourceLiterals[i];
  }
  return source;
}
@param {Array.<string>} sourceLiterals
@return {string}