"ACCOUNTID" variable on Deals module in v2 API

"ACCOUNTID" variable on Deals module in v2 API

I have a function associated with the Tasks module, written in the v1 API.
In my particular case, when a Task is related to a Deal, (rather than directly related to an Account) I need to be able to draw information from the account related to the Deal.

I was previously able to accomplish this with the following code - the Account ID is stored in the "ACCOUNTID" field:
    dealDetails = zoho.crm.v1.getRecordById("Potentials",input_dealID);
    accountID = dealDetails.get("ACCOUNTID");

This approach does not work with the v2 API.
I've not able to pass the Account ID from the Task itself, since the Task is not "directly" related to the Account.
Any help appreciated.