code: def api_post_multipart(self, action, data, binary_data_param):
          
          binary_data = {}
          data = data.copy()
  
          try:
              file_handles = []
              for param in binary_data_param:
                  if param in data:
                      binary_data[param] = file_handle = open(data[param], 'r')
                      file_handles.append(file_handle)
                      del data[param]
              json_payload = self._prepare_json_payload(data)
  
              return self._http_request(action, json_payload, "POST", binary_data)
          finally:
              for file_handle in file_handles:
                  file_handle.close()
docs: Perform an HTTP Multipart POST request, using the shared-secret auth hash.
          @param action: API action call
          @param data: dictionary values
          @param: binary_data_params: array of multipart keys