I am learning tensorflow, I picked up the following code from the tensorflow website. According to my understanding, axis=0 is for rows and axis=1 is for columns.

How are they getting output mentioned in comments? I have mentioned output according to my thinking against ##.

```
import tensorflow as tf

x = tf.constant([[1, 1, 1], [1, 1, 1]])
tf.reduce_sum(x, 0)  # [2, 2, 2] ## [3, 3]
tf.reduce_sum(x, 1)  # [3, 3] ##[2, 2, 2]
tf.reduce_sum(x, [0, 1])  # 6 ## Didn't understand at all.

```