Function easyenv::get_env_num

pub fn get_env_num<T>(env_name: &str, default: T) -> Result<T, EnvError> where
    T: FromStr + Display,
    T::Err: Debug, 

Get an environment variable as a number, or fall back to the provided default if not set. If the env var is present but can't be parsed, an error is returned instead.