def update
      @arm = Arm.find(params[:id])
      authorize! :update, @arm
      if @arm.update(arm_params)
        redirect_to arm_path(@arm),
                    notice: "Arm was successfully updated.",
                    only: true
      else
        render :edit
      end
    end
def update
      @arm = Arm.find(params[:id])
      authorize! :update, @arm
      if @arm.update(arm_params)
        redirect_to arm_path(@arm),
                    notice: "Arm was successfully updated.",
                    only: true
      else
        render :edit
      end
    end
PATCH/PUT /think_feel_do_dashboard/arms/1