code: def _default_body(self):
          
          if not self.data:
              return ""
          if self.content_type == 'application/json':
              import json
              return json.dumps(self.data)
          elif self.content_type == 'application/x-www-form-urlencoded':
              import urllib
              return urllib.urlencode(self.data)
          else:
              raise NotImplementedError(
                  "You must manually encode the request "
                  "body for '{}'".format(self.content_type)
              )
docs: If the body is not passed in by the user try to create one
          using the given data parameters.