returns the span of a cell
| row | number | the row index of the cell |
| column | number | the column index of the cell |
| page | string | optional, the name of the sheet |
| array | an array describing the span, or undefined if the cell has no span |
const span = $$("ssheet").getSpan(1, 1);
// returns [1, 1, 5, 1]
The method returns an array in the same format as the spans field in the data:
If the cell has no span, the method returns undefined.