how to make only one corner of a container circular in flutter code example

Example: round container flutter

Container(
      width: screenWidth / 7,
      decoration: BoxDecoration(
        border: Border.all(
          color: Colors.red[500],
        ),
      ),
      child: Padding(
        padding: EdgeInsets.all(5.0),
        child: Column(
          children: <Widget>[
            Text(
              '6',
              style: TextStyle(
                  color: Colors.red[500],
                  fontSize: 25),
            ),
            Text(
             'sep',
              style: TextStyle(
                  color: Colors.red[500]),
            )
          ],
        ),
      ),
    );