def _default_body(self):
        """ If the body is not passed in by the user try to create one
        using the given data parameters. 
        """
        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)
            )
If the body is not passed in by the user try to create one
        using the given data parameters.