// scanners.
func (s *Scanner) Scan() bool {
	if s.done {
		return false
	}
	s.scanCalled = true
	// Loop until we have a token.
	for {
		// See if we can get a token with what we already have.
		// If we've run out of data but have an error, give the split function
		// a chance to recover any remaining, possibly empty token.
		if s.end > s.start || s.err != nil {

   * methods to accept null. We could avoid having unchecked casts in Converter.java itself if we
   * could perform a cast to LegacyConverter, but we can't because it's an internal-only class.
   *
   * TODO(cpovirk): So make it part of the open-source build, albeit package-private there?
   *
   * So we use uncheckedCastNullableTToT here. This is a weird usage of that method: The method is

         */
        return 0;
    }


    /*
     * We overload this method from ServerMessageBlock because
     * we want writeAndXWireFormat to write the parameterWords
     * and bytes. This is so we can write batched smbs because
     * all but the first smb of the chaain do not have a header
     * and therefore we do not want to writeHeaderWireFormat. We
     * just recursivly call writeAndXWireFormat.
     */

      } finally {
        monitor.leave();
      }
    } else {
      // It is possible due to races that we are currently in the expected state even though we
      // timed out. e.g. if we weren't event able to grab the lock within the timeout we would never
      // even check the guard. I don't think we care too much about this use case but it could lead
      // to a confusing error message.

         */
        return 0;
    }

    /* 
     * We overload this method from ServerMessageBlock because
     * we want writeAndXWireFormat to write the parameterWords
     * and bytes. This is so we can write batched smbs because
     * all but the first smb of the chaain do not have a header
     * and therefore we do not want to writeHeaderWireFormat. We
     * just recursivly call writeAndXWireFormat.
     */ 

      // e.g. a certificate pinning error.
      return false
    }
    // An example of one we might want to retry with a different route is a problem connecting to a
    // proxy and would manifest as a standard IOException. Unless it is one we know we should not
    // retry, we return true and try a new route.
    return true
  }

  /**

```

There are some differences with the code for the SQLAlchemy tutorial.

We don't pass a `db` attribute around. Instead we use the models directly. This is because the `db` object is a global object, that includes all the connection logic. That's why we had to do all the `contextvars` updates above.

Aso, when returning several objects, like in `get_users`, we directly call `list`, like in:

```Python
list(models.User.select())
```

    using a job called "copybara".

**5. Copy to Google Internal codebase and run internal CI**

-   Once the PR is in the Google codebase, we make sure it integrates well with
    its dependencies and the rest of the system.
-   Rarely, If the tests fail at this stage, we cannot merge the code.
-   If needed, we may come to you to make some changes. At times, it may not be

1. If the destination has a waypoint proxy, we must send to it to the waypoint (using HBONE).
   When we do this, we will want to preserve the original destination Service IP, as the waypoint can do a better job picking a backend pod than we can.

Let's continue from the previous example. We wanted to **annotate the function with one type** but return something that includes **more data**.

We want FastAPI to keep **filtering** the data using the response model.

In the previous example, because the classes were different, we had to use the `response_model` parameter. But that also means that we don't get the support from the editor and tools checking the function return type.