Compare two commits using Azure Devops api and get response in `.diff` format

I want to compare two commits in Azure DevOps and get the response in git .diff format.

I tried the APIs listed in doc https://docs.microsoft.com/en-us/rest/api/azure/devops/git/diffs/get?view=azure-devops-rest-6.0.

But it only returns the diff in JSON format.

How can I get the data in the git diff format?