async fn get_parameter_history(
        &self,
        input: GetParameterHistoryRequest,
    ) -> Result<GetParameterHistoryResult, RusotoError<GetParameterHistoryError>> {
        let mut request = self.new_signed_request("POST", "/");
        request.add_header("x-amz-target", "AmazonSSM.GetParameterHistory");
        let encoded = serde_json::to_string(&input).unwrap();
        request.set_payload(Some(encoded));

        let response = self
            .sign_and_dispatch(request, GetParameterHistoryError::from_response)
            .await?;
        let mut response = response;
        let response = response.buffer().await.map_err(RusotoError::HttpDispatch)?;
        proto::json::ResponsePayload::new(&response).deserialize::<GetParameterHistoryResult, _>()
    }
<p>Retrieves the history of all changes to a parameter.</p>
rusoto/services/ssm/src/generated.rs