How to use the rx-jupyter.sessions.destroy function in rx-jupyter

if (!kernel.id || !kernel.sessionId) {
        return of(
          actions.killKernelFailed({
            error: new Error(
              "websocket kernel epic can only kill websocket kernels with an id"
            ),
            kernelRef: action.payload.kernelRef
          })
        );
      }

      // TODO: If this was a kernel language change, we shouldn't be using this
      //       kill kernel epic because we need to make sure that creation happens
      //       after deletion
      return sessions.destroy(serverConfig, kernel.sessionId).pipe(
        mergeMap(() =>
          action.payload.dispose && action.payload.kernelRef
            ? of(
                actions.killKernelSuccessful({
                  kernelRef: action.payload.kernelRef
                }),
                actions.disposeKernel({ kernelRef: action.payload.kernelRef })
              )
            : of(
                actions.killKernelSuccessful({
                  kernelRef: action.payload.kernelRef
                })
              )
        ),
        catchError(err =>
          of(

if (kernel.type !== "websocket" || !kernel.id || !kernel.sessionId) {
        return of(
          actions.killKernelFailed({
            error: new Error(
              "websocket kernel epic can only kill websocket kernels with an id"
            ),
            kernelRef: action.payload.kernelRef
          })
        );
      }

      // TODO: If this was a kernel language change, we shouldn't be using this
      //       kill kernel epic because we need to make sure that creation happens
      //       after deletion
      return sessions.destroy(serverConfig, kernel.sessionId).pipe(
        map(() =>
          actions.killKernelSuccessful({
            kernelRef: action.payload.kernelRef
          })
        ),
        catchError(err =>
          of(
            actions.killKernelFailed({
              error: err,
              kernelRef: action.payload.kernelRef
            })
          )
        )
      );
    })
  );