default rust struct initialization

gistfile1.txt

 44     let identities = sesclient
 45         .send_email(rusoto_ses::SendEmailRequest {
 46             destination: rusoto_ses::Destination {
 47                 to_addresses: Some(vec!["[email protected]".to_string()]),
 48                 ..rusoto_ses::Destination::default()
 49             },
 50             message: rusoto_ses::Message {
 51                 subject: rusoto_ses::Content {
 52                     data: "Test message".to_string(),
 53                     ..rusoto_ses::Content::default()
 54                 },
 55                 body: rusoto_ses::Body {
 56                     text: Some(rusoto_ses::Content {
 57                         data: "message subject".to_string(),
 58                         ..rusoto_ses::Content::default()
 59                     }),
 60                     ..rusoto_ses::Body::default()
 61                 },
 62             },
 63             source: "[email protected]".to_string(),
 64             ..rusoto_ses::SendEmailRequest::default()
 65         })
 66         .sync()
 67         .unwrap();