Then your API will (let's imagine):

* Send the invoice to some customer of the external developer.
* Collect the money.
* Send a notification back to the API user (the external developer).
    * This will be done by sending a POST request (from *your API*) to some *external API* provided by that external developer (this is the "callback").

## The normal **FastAPI** app

* Update GitHub action issue-manager. PR [#1520](https://github.com/tiangolo/fastapi/pull/1520).
* Add new links:
    * **English articles**:
        * [Real-time Notifications with Python and Postgres](https://wuilly.com/2019/10/real-time-notifications-with-python-and-postgres/) by [Guillermo Cruz](https://wuilly.com/).

    cycle.remove();
    assertEquals(Collections.emptyList(), iterable);
    assertFalse(cycle.hasNext());
  }

  /** An Iterable whose Iterator is rigorous in checking for concurrent modification. */
  private static final class PickyIterable<E> implements Iterable<E> {
    final List<E> elements;
    int modCount = 0;

    PickyIterable(E... elements) {

              }
              i++;
              /*
               * The cast is safe because of the containsKey check in hasNext(). (That means it's
               * unsafe under concurrent modification, but all bets are off then, anyway.)
               */
              return uncheckedCastNullableTToT(map.get(key));
            }

            @Override
            public void remove() {

    *   C-API functions `TF_StringDecode`, `TF_StringEncode`, and
        `TF_StringEncodedSize` are no longer relevant and have been removed; see
        `core/platform/ctstring.h` for string access/modification in C.
    *   `tensorflow.python`, `tensorflow.core` and `tensorflow.compiler` modules
        are now hidden. These modules are not part of TensorFlow public API.