WP Query category not in

not in:

              $args = array(
                'post_type' => 'post',
                'posts_per_page' => 3,
                'post_status' => 'publish',
                'order' => 'DESC',
                'order_by' => 'date',
                'tax_query' => array(
                  array(
                    'taxonomy'=>'category',
                    'field' => 'slug',
                    'terms' => 'events',
                    'operator' => 'NOT IN',
                  )
                )
              );

category in:

              $args = array(
                'post_type' => 'post',
                'posts_per_page' => 3,
                'post_status' => 'publish',
                'order' => 'DESC',
                'order_by' => 'date',
                'tax_query' => array(
                  array(
                    'taxonomy'=>'category',
                    'field' => 'slug',
                    'terms' => 'events',
                  )
                )
              );