value equal to: 'first', 'last' | boolean | list with values of type: boolean If true, the user can select the column by clicking on the checkbox or radio button in the column. If there are multiple header rows, true will display the input on each row. If `last`, the input will only appear on the last header row. If `first` it will only appear on the first header row. These are respectively shortcut equivalents to `[false, ..., false, true]` and `[true, false, ..., false]`. If there are merged, multi-header columns then you can choose which column header row to display the input in by supplying an array of booleans. For example, `[true, false]` will display the `selectable` input on the first row, but now on the second row. If the `selectable` input appears on a merged columns, then clicking on that input will select *all* of the merged columns associated with it. The table-level prop `column_selectable` is used to determine the type of column selection to use.