*/
  protected long edgeCount() {
    long degreeSum = 0L;
    for (N node : nodes()) {
      degreeSum += degree(node);
    }
    // According to the degree sum formula, this is equal to twice the number of edges.
    checkState((degreeSum & 1) == 0);
    return degreeSum >>> 1;
  }

  /**
   * An implementation of {@link BaseGraph#edges()} defined in terms of {@link Graph#nodes()} and

                        } else {
                            return -1;
                        }
                    });
                    // Remove duplicates (equal adjacent elements) - a new, un@Incubating type will be here twice, as 2 errors are reported; use stringified JSON to compare
                    // Filtering an array is NOT in place

func (w *Writer) Close() error {
	if w.last != nil && !w.last.closed {
		if err := w.last.close(); err != nil {
			return err
		}
		w.last = nil
	}
	if w.closed {
		return errors.New("zip: writer closed twice")
	}
	w.closed = true

	// write central directory
	start := w.cw.count
	for _, h := range w.dir {
		var buf [directoryHeaderLen]byte
		b := writeBuf(buf[:])
		b.uint32(uint32(directoryHeaderSignature))

    .header("User-Agent", "OkHttp Example")
    .build();

Response response = client.newCall(request).execute();
response.body().close();
```

When we run this code, the interceptor runs twice. Once for the initial request to `http://www.publicobject.com/helloworld.txt`, and another for the redirect to `https://publicobject.com/helloworld.txt`.

```

	ctx, cancel := context.WithCancel(context.Background())

	if !dm.GetLock(ctx, cancel, id, source, Options{Timeout: 5 * time.Minute}) {
		t.Fatal("GetLock() should be successful")
	}

	// Make it run twice.
	timer := time.NewTimer(testDrwMutexRefreshInterval * 2)

	select {
	case <-ctx.Done():
		t.Fatal("Lock context canceled which is not expected")
	case <-timer.C:
	}

          result.throwException();
          return 0; // Not called.
        }
      }
    }
  }

  /** Returns a new CharBuffer identical to buf, except twice the capacity. */
  private static CharBuffer grow(CharBuffer buf) {
    char[] copy = Arrays.copyOf(buf.array(), buf.capacity() * 2);
    CharBuffer bigger = CharBuffer.wrap(copy);

          result.throwException();
          return 0; // Not called.
        }
      }
    }
  }

  /** Returns a new CharBuffer identical to buf, except twice the capacity. */
  private static CharBuffer grow(CharBuffer buf) {
    char[] copy = Arrays.copyOf(buf.array(), buf.capacity() * 2);
    CharBuffer bigger = CharBuffer.wrap(copy);

          boolean firstCall = true;

          @Override
          public boolean processBytes(byte[] buf, int off, int len) throws IOException {
            assertTrue("consume() called twice", firstCall);
            firstCall = false;
            return false;
          }

          @Override
          public @Nullable Void getResult() {
            return null;
          }
        };

    }

    if (failedConnection != null) {
      val retryRoute = retryRoute(failedConnection)
      if (retryRoute != null) {
        // Lock in the route because retryRoute() is racy and we don't want to call it twice.
        nextRouteToTry = retryRoute
        return true
      }
    }

    // If we have a routes left, use 'em.
    if (routeSelection?.hasNext() == true) return true

          signalledCallback = true
          responseCallback.onResponse(this@RealCall, response)
        } catch (e: IOException) {
          if (signalledCallback) {
            // Do not signal the callback twice!
            Platform.get().log("Callback failure for ${toLoggableString()}", Platform.INFO, e)
          } else {
            responseCallback.onFailure(this@RealCall, e)
          }
        } catch (t: Throwable) {