try {
        in.close();
      } finally {
        in = null;
      }
    }
  }

  /** Closes the current input stream and opens the next one, if any. */
  private void advance() throws IOException {
    close();
    if (it.hasNext()) {
      in = it.next().openStream();
    }
  }

  @Override
  public int available() throws IOException {
    if (in == null) {
      return 0;
    }

      String nextSeparator = "";
      StringBuilder builder = new StringBuilder(32).append(className).append('{');
      for (ValueHolder valueHolder = holderHead.next;
          valueHolder != null;
          valueHolder = valueHolder.next) {
        Object value = valueHolder.value;
        if (valueHolder instanceof UnconditionalValueHolder
            || (value == null
                ? !omitNullValuesSnapshot

        @Override
        protected @Nullable String computeNext() {
          if (lines.hasNext()) {
            String next = lines.next();
            // skip last line if it's empty
            if (lines.hasNext() || !next.isEmpty()) {
              return next;
            }
          }
          return endOfData();
        }
      };
    }

    @Override

        @Override
        protected @Nullable String computeNext() {
          if (lines.hasNext()) {
            String next = lines.next();
            // skip last line if it's empty
            if (lines.hasNext() || !next.isEmpty()) {
              return next;
            }
          }
          return endOfData();
        }
      };
    }

    @Override

}

// Results returns the results from the remote server one by one.
// If any error is returned by the callback, the stream will be canceled.
// If the context is canceled, the stream will be canceled.
func (s *Stream) Results(next func(b []byte) error) (err error) {
	done := false
	defer func() {
		if s.cancel != nil {
			s.cancel(err)
		}

		if !done {
			// Drain channel.
			for range s.responses {
			}
		}
	}()

    assertThrows(
        ConcurrentModificationException.class,
        () -> {
          Iterator<Entry<K, V>> iterator = getMap().entrySet().iterator();
          put(e3());
          iterator.next();
        });
  }

  @MapFeature.Require({FAILS_FAST_ON_CONCURRENT_MODIFICATION, SUPPORTS_PUT})
  @CollectionSize.Require(absent = ZERO)
  public void testPutAbsentConcurrentWithKeySetIteration() {
    assertThrows(

        }

        return false
      }

      override fun next(): String {
        if (!hasNext()) throw NoSuchElementException()
        val result = nextUrl!!
        nextUrl = null
        canRemove = true
        return result
      }

      override fun remove() {
        check(canRemove) { "remove() before next()" }
        delegate.remove()
      }
    }
  }

I'll show you some concrete examples in the next chapters.

---

Then the next concepts to consider are all about the program running your actual API (e.g. Uvicorn).

## Program and Process { #program-and-process }

      @Override
      public boolean hasNext() {
        return entryItr.hasNext();
      }

      @Override
      public V next() {
        return entryItr.next().getValue();
      }
    };
  }

  @Override
  public boolean contains(@Nullable Object object) {
    return object != null && Iterators.contains(iterator(), object);
  }

  @Override

    private final ReferenceEntry<K, V> next;

    public DummyEntry(K key, int hash, ReferenceEntry<K, V> next) {
      this.key = key;
      this.hash = hash;
      this.next = next;
    }

    public static <K, V> DummyEntry<K, V> create(
        K key, int hash, @Nullable ReferenceEntry<K, V> next) {
      return new DummyEntry<>(key, hash, next);
    }

    public void clearKey() {