{* ../../docs_src/query_params/tutorial004_py310.py hl[6,8] *}

## Required query parameters { #required-query-parameters }

When you declare a default value for non-path parameters (for now, we have only seen query parameters), then it is not required.

If you don't want to add a specific value but just make it optional, set the default as `None`.

But when you want to make a query parameter required, you can just not declare any default value:

    //    were added to the queue. It's easily possible for one thread to take the head of the
    //    queue, immediately followed by another thread taking the next element in the queue. That
    //    second thread can then dispatch to the subscriber it took before the first thread does.
    //
    // All this makes me really wonder if there's any value in queueing here at all. A dispatcher

        return;
      }
      executed = true;
      list = runnables;
      runnables = null; // allow GC to free listeners even if this stays around for a while.
    }
    // If we succeeded then list holds all the runnables we to execute. The pairs in the stack are
    // in the opposite order from how they were added so we need to reverse the list to fulfill our
    // contract.

   *
   * <p>This bug is this: if you create an iterator from a TreeSet and call next() on that iterator
   * when hasNext() is false, so that next() throws a NoSuchElementException, then subsequent calls
   * to remove() will incorrectly throw an IllegalStateException, instead of removing the last
   * element returned.
   *
   * <p>See <a href="https://bugs.openjdk.org/browse/JDK-6529795">JDK-6529795</a>

  private static final long K3 = 0xc6a4a7935bd1e995L;

  @Override
  public HashCode hashBytes(byte[] input, int off, int len) {
    checkPositionIndexes(off, off + len, input.length);
    return HashCode.fromLong(fingerprint(input, off, len));
  }

  @Override
  public int bits() {
    return 64;
  }

  @Override
  public String toString() {
    return "Hashing.fingerprint2011()";

                sb.append("Try downloading the file manually from the project website.");
            }

            sb.append(LS);
            sb.append(LS);
            sb.append(indentation);
            sb.append("Then, install it using the command: ");
            sb.append(LS);
            sb.append(indentation);
            sb.append("    mvn install:install-file -DgroupId=");
            sb.append(groupId);

	var texts [31]string
	str := ""
	all := ""
	for i := 0; i < len(texts)-1; i++ {
		texts[i] = str + "\n"
		all += texts[i]
		str += string(rune(i%26 + 'a'))
	}
	texts[len(texts)-1] = all

	for h := 0; h < len(texts); h++ {
		text := texts[h]
		for i := 0; i < len(readMakers); i++ {
			for j := 0; j < len(bufreaders); j++ {
				for k := 0; k < len(bufsizes); k++ {
					readmaker := readMakers[i]

   * without the guard being satisfied (due to timeout, but not interrupt) can then immediately exit
   * the monitor without signalling. If it timed out without being signalled, it does not need to
   * "pass on" the signal to another thread. If it *was* signalled, then its guard must have been
   * satisfied at the time of signal, and has since been modified by some other thread to be

	"strings"
	"testing"
	"time"
)

func TestIsValidDBNameChar(t *testing.T) {
	for _, db := range []string{"db", "dbName", "db_name", "db1", "1dbname", "db$name"} {
		if fields := strings.FieldsFunc(db, IsValidDBNameChar); len(fields) != 1 {
			t.Fatalf("failed to parse db name %v", db)
		}
	}
}

func TestCheckTruth(t *testing.T) {
	checkTruthTests := []struct {
		v   string
		out bool
	}{
		{"123", true},

				// With newer config disallowing changing / turning off
				// notification targets without removing ARN in notification
				// configuration we won't see this problem anymore.
				if reflect.DeepEqual(queue.ARN, arnErr.ARN) && i < len(config.QueueList) {
					config.QueueList = append(config.QueueList[:i],
						config.QueueList[i+1:]...)
				}
				// This is a one time activity we shall do this
				// here and allow stale ARN to be removed. We shall