code: def post(self, endpoint, payload=None):
          
          nonce = int(time.time() * 10000)
          hmac_msg = str(nonce) + self._client_id + self._api_key
          signature = hmac.new(
              key=self._hmac_key,
              msg=hmac_msg.encode('utf-8'),
              digestmod=hashlib.sha256
          ).hexdigest()
  
          if payload is None:
              payload = {}
          payload['key'] = self._api_key
          payload['nonce'] = nonce
          payload['signature'] = signature
  
          response = self._session.post(
              url=self._url + endpoint,
              json=payload,
              timeout=self._timeout
          )
          return self._handle_response(response)
docs: Send an HTTP POST request to QuadrigaCX.
  
          :param endpoint: API endpoint.
          :type endpoint: str | unicode
          :param payload: Request payload.
          :type payload: dict
          :return: Response body from QuadrigaCX.
          :rtype: dict
          :raise quadriga.exceptions.RequestError: If HTTP OK was not returned.