svoid gazelle_gatherFulfillments(L<GazelleLine> lines, L<GazelleFulfillment> list_out, O... _) {

  Int maxEntries = cast optPar maxEntries(_);

  Flag cancel = cast optPar cancel(_);

  bool debug = boolPar debug(_);

  GazelleEvalContext ctx = cast optPar ctx(_);

  if (ctx == null) ctx = dm_gazelle_stdEvalContext(dm_gazelle_rulesOnFacts());

  else {

    ctx = gazelle_cloneCtx(ctx);

    ctx.engine.dropRulesWhere(r -> !gazelle_isRuleOnFacts(r.text, r.comments));

  }

  if (debug) print("Rules: " + l(ctx.engine.rules));

  for (GazelleLine line : lines) pcall {

    L<GazelleTree> children = gazelle_getChildren(GazelleTree(ctx, line.text), _);

    if (debug) print("line " + line + ": children: " + children);

    for (GazelleTree t : gazelle_dropUnsatisfiedEntries(children)) pcall {

      if (flagIsUp(cancel) || maxEntries != null && l(list_out) >= maxEntries) ret with print("Cancel");

      GazelleFulfillment f = nu GazelleFulfillment(

        line := t.parent.line,

        varMap := struct(t.varMap()),

        rule := t.ruleID(),

        matchedRuleStruct := struct(t.mr),

        context := "discord msg " + line.msgID);

      if (debug) printStruct(f);

      list_out.add(f);

    }

  }

}