async fn describe_activations(
        &self,
        input: DescribeActivationsRequest,
    ) -> Result<DescribeActivationsResult, RusotoError<DescribeActivationsError>> {
        let mut request = self.new_signed_request("POST", "/");
        request.add_header("x-amz-target", "AmazonSSM.DescribeActivations");
        let encoded = serde_json::to_string(&input).unwrap();
        request.set_payload(Some(encoded));

        let response = self
            .sign_and_dispatch(request, DescribeActivationsError::from_response)
            .await?;
        let mut response = response;
        let response = response.buffer().await.map_err(RusotoError::HttpDispatch)?;
        proto::json::ResponsePayload::new(&response).deserialize::<DescribeActivationsResult, _>()
    }
<p>Describes details about the activation, such as the date and time the activation was created, its expiration date, the IAM role assigned to the instances in the activation, and the number of instances registered by using this activation.</p>
rusoto/services/ssm/src/generated.rs