// post is the text from e.g. https://gazelle.rocks/131422
sS gazelle_ai_addFalseNegativeToDetector(S post) {
  S detectorCode = trim(first(splitAtEmptyLines(getColonHeadingSection("Detector code", post))));
  print("Detector: " + detectorCode);
  LS falseNegatives = lmap afterColon(linesStartingWith("False negative", post);
  S falseNegative = random(falseNegatives);
  if (falseNegative == null) null;
  print("Selecting false negative: " + falseNegative);
  S matchExpression = firstQuoted(detectorCode);
  print(+matchExpression);
  S newMatchExpression = matchExpression + ", " + falseNegative;
  print(+newMatchExpression);
  S newCode = replace(detectorCode, quote(matchExpression), quote(newMatchExpression));
  print(+newCode);
  ret newCode;
}