Function togglePlotSelection

togglePlotSelection(
    selection: Set<number>,
    channel: number,
    checked: boolean,
): Set<number> | null
Returns the selection after ticking or unticking a channel.
Parameters
- selection: Set<number>
  Current selection.
- channel: number
  LabJack channel number.
- checked: boolean
  New checkbox state.
Returns Set<number> | null
A new set, or null when the change is refused (adding a third channel).
- Defined in plot/channel.ts:166