fn generate_unique_name(prefix: &str) -> String {
    let mut rng = rand::thread_rng();
    format!(
        "{}-{}",
        prefix,
        std::iter::repeat(())
            .map(|()| rng.sample(Alphanumeric))
            .take(AWS_SERVICE_RANDOM_SUFFIX_LENGTH)
            .collect::<String>()
    )
    .to_lowercase()
}
Generates a random name for an AWS service by appending a random sequence of
ASCII characters to the specified prefix.
Keeps it lower case to work with S3 requirements as of 3/1/2018.
integration_tests/tests/elastictranscoder.rs