Perform /login.

        Args:
            login_type (str): The value for the 'type' key.
            **kwargs: Additional key/values to add to the JSON submitted.

def login(self, login_type, **kwargs):
        """Perform /login.

        Args:
            login_type (str): The value for the 'type' key.
            **kwargs: Additional key/values to add to the JSON submitted.
        """
        content = {
            "type": login_type
        }
        for key in kwargs:
            if kwargs[key]:
                content[key] = kwargs[key]

        return self._send("POST", "/login", content)