public SignatureEnvelopeResponse ModifyEnvelope(string envelopeId, SignatureEnvelopeSettings settings)
        {
            var template   = SignatureApiUriTemplates.BuildUriTemplate(SignatureApiUriTemplates.Envelope);
            var parameters = new NameValueCollection
            {
                { "userId", UserId },
                { "envelopeId", envelopeId }
            };

            using (var content = HttpContentNetExtensions.CreateJsonNetDataContract(settings))
            {
                var response = SubmitRequest <SignatureEnvelopeResponse>(template, parameters, "POST", content);
                return(response);
            }
        }
        public SignatureEnvelopeResponse ModifyEnvelope(string envelopeId, SignatureEnvelopeSettings settings)
        {
            var template = SignatureApiUriTemplates.BuildUriTemplate(SignatureApiUriTemplates.Envelope);
            var parameters = new NameValueCollection
            {
                { "userId", UserId },
                { "envelopeId", envelopeId }
            };

            using (var content = HttpContentNetExtensions.CreateJsonNetDataContract(settings))
            {
                var response = SubmitRequest<SignatureEnvelopeResponse>(template, parameters, "POST", content);
                return response;
            }
        }