setSharedFormula(id, formula, sharedRef) {
        this.clear();

        this._formulaType = "shared";
        this._sharedFormulaId = id;
        this._formula = formula;
        this._formulaRef = sharedRef;
    }
Set a shared formula on the cell.
@param {number} id - The shared formula index.
@param {string} [formula] - The formula (if the reference cell).
@param {string} [sharedRef] - The address of the shared range (if the reference cell).
@returns {undefined}
@ignore