Could have a feature when the parameters accept only a couple of predefined options/values,the parameters could be chosen by s drop-down list?

[Prologued]

Sometimes custom function might have parameters which accept only a couple of predefined options/values. It would be nice to have a feature which allows the user to see those possible options (for selection, like in a drop-down list or similar) as soon as he starts typing in the custom function into a cell.