How to use the streams.WritableStream function in streams

});
      socket.addEventListener('close', () => {
        try {
          c.close();
        } catch(e) {
          // The stream has already been closed.
        }
      });
      socket.addEventListener('error', (evt) => c.error(evt.data || evt));
    },
    cancel: function() {
      maybeCloseSocket();
    }
  });

  this.writable = new streams.WritableStream({
    start: function(error) {
      socket.addEventListener('error', (evt) => error(evt.data || evt));
    },
    write: function(chunk) {
      socket.send(chunk);
      // We don't know when send completes, so this is synchronous.
    },
    close: function() {
      maybeCloseSocket();
    }
  })
}

if (knownFilteredSet.delete(change.id)) {
              change = shallowClone(change);
              mutateChangeToResembleDeletion(change);
              enqueue(change);
            }
          }
          done();
        });
      }
    },
    writableStrategy: new CountQueuingStrategy({ highWaterMark: 1 }),
    readableStrategy: new CountQueuingStrategy({ highWaterMark: 1 })
  });

  //bufferingStream.readable.pipeTo(gatherStream.writable);
  gatherStream.readable.pipeThrough(filterStream).pipeTo(new WritableStream({
    start() {
    },
    write(change) {
      onFilteredUpdate(change);
    },
    close() {
      // I don't think anything actually cares?  Unless we should be propagating
      // through to the moot callback?
    },
    abort(ex) {
      logic(ctx, 'filteringStreamAbortError', { ex, stack: ex.stack });
    }
  }, new CountQueuingStrategy({ highWaterMark: 1 })));

  return {
    /**