How to get the role information of a user assigned with different roles at subscription level using REST API

Hi,

I assigned a user in the Default directory to be a Contributor/Owner/Reader on the subscription level.
It shows as below in the portal

How to get this information using REST API with input as objectId, SubscriptionId, DirectoryId.
ObjectId is the ID for the user registered in the Azure AD.

Output: Role name as on the portal.

FYI: I used this link MSDN Link. But, It dint serve my purpose. 


Thanks in advance. 
Regards,
Rahul

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rahul mohan