public static OkSignResponse UploadPdfForSignature(string fileName, FormDescriptor formDescriptor, string authorizationHeader, out string error, int timeOutSec = 10, CancellationTokenSource cancellationTokenSource = null)
public static async Task<(OkSignResponse response, string error)> UploadPdfForSignatureAsync(string fileName, FormDescriptor formDescriptor, string authorizationHeader, int timeOutSec = 10)

public static bool Remove(string docId, string authorizationHeader, out string error, int timeOutSec = 10)
public static async Task<(bool result, string error)> RemoveAsync(string docId, string authorizationHeader, int timeOutSec = 10)

public static OkSignResponse.FileInfoDescriptor DocumentExists(string docId, string authorizationHeader, out string error, int timeOutSec = 10)
public static async Task<(OkSignResponse.FileInfoDescriptor result, string error)> DocumentExistsAsync(string docId, string authorizationHeader, int timeOutSec = 10)

public static byte[] DocumentRetrieve(string docId, string authorizationHeader, out string error, int timeOutSec = 10)
public static async Task<(byte[] result, string error)> DocumentRetrieveAsync(string docId, string authorizationHeader, int timeOutSec = 10)

public static DocumentStatusRet DocumentStatus(string docId, string authorizationHeader, out string error, int timeOutSec = 10)
public static async Task<(DocumentStatusRet, string error)> DocumentStatusAsync(string docId, string authorizationHeader, int timeOutSec = 10)