@property<EOL><INDENT>def duration(self):<DEDENT>
if self.ended_timestamp is None:<EOL><INDENT>return datetime.datetime.utcnow() - self.message.created_at<EOL><DEDENT>else:<EOL><INDENT>return self.ended_timestamp - self.message.created_at<EOL><DEDENT>
Queries the duration of the call.

        If the call has not ended then the current duration will
        be returned.

        Returns
        ---------
        datetime.timedelta
            The timedelta object representing the duration.