Function ec2_response 

pub fn ec2_response(action: &str, request_id: &str, body: &str) -> String

Wrap an operation’s result body in the ec2Query response envelope.

<?xml version="1.0" encoding="UTF-8"?>
<RunInstancesResponse xmlns="http://ec2.amazonaws.com/doc/2016-11-15/">
  <requestId>{request_id}</requestId>
  {body}
</RunInstancesResponse>

body is the already-rendered, already-escaped inner XML (use the element and list helpers in this module to build it).