get_document（）的python签名是什么？
当我这样调用它时，我会得到下面的异常（这是C#签名）：

docstream = envelopes_api.get_document(account_id, envelope_id, document_id)

docusign_esign.rest.ApiException: (400)
Reason: Bad Request
HTTP response headers: HTTPHeaderDict({'Cache-Control': 'no-cache', 'Content-Length': '159', 'Content-Type': 'application/json; charset=utf-8', 'X-DocuSign-TraceToken': '961f6b00-3a25-4d47-895d-987ebe85a1f5', 'Date': 'Wed, 15 Aug 2018 13:29:31 GMT', 'Strict-Transport-Security': 'max-age=31536000; includeSubDomains'})
HTTP response body: b'{\r\n  "errorCode": "INVALID_REQUEST_PARAMETER",\r\n  "message": "The request contained at least one invalid parameter. Invalid value specified for envelopeId."\r\n}'