Configures --region option for CLI

    :param f: Callback Function to be passed to Click

def region_option(f):
    """
    Configures --region option for CLI

    :param f: Callback Function to be passed to Click
    """
    def callback(ctx, param, value):
        state = ctx.ensure_object(Context)
        state.region = value
        return value

    return click.option('--region',
                        expose_value=False,
                        help='Set the AWS Region of the service (e.g. us-east-1).',
                        callback=callback)(f)