{exp:rest} - Dynamically access keys

Question

I am using the Rest plugin.

Let us say that my API outputs a JSON like this

{
  "8741" : "some data 1 ...",
  "27848" : "some data 2 ...",
  ...
} 

I want to access the data via its index. I will know what the index is at runtime. So how do I access the data?

{exp:rest ...}
 {8741}  <-- can't define this literally since the index is going to be set at runtime
{/exp:rest}