API client is mainly responible for making the HTTP call to the API backend
 /// <summary>
 /// Initializes a new instance of the <see cref="FileApi"/> class.
 /// </summary>
 /// <param name="apiClient"> an instance of ApiClient (optional)
 /// <returns></returns>
 public FileApi(ApiClient apiClient = null) {
   if (apiClient == null) { // use the default one in Configuration
     this.apiClient = Configuration.apiClient; 
   } else {
     this.apiClient = apiClient;
   }
 }
 public static void ClassInit(TestContext context)
 {
     client = new ApiClient("https://platform.systran.net:8904");
     Configuration.apiClient = client;
     if (!File.Exists("../../apiKey.txt"))
         throw new Exception("To properly run the tests, please add an apiKey.txt file containing your api key in the SystranClientMultimodalApiLibTests folder or edit the test file with your key");
     Dictionary<String, String> keys = new Dictionary<String, String>();
     string key;
     using (StreamReader streamReader = new StreamReader("../../apiKey.txt", Encoding.UTF8))
     {
         key = streamReader.ReadToEnd();
     }
     keys.Add("key", key); Configuration.apiKey = keys; Configuration.apiKey = keys;
     if (keys.Count == 0)
         throw new Exception("No api key found, please check your apiKey.txt file");
     Configuration.apiKey = keys;
     fileApi = new FileApi(Configuration.apiClient);
 }