Why AES code is working even with 3 Rows

First of all, I am a student, so even if most of you think it is a useless question, don't dishearten me as it is a platform for me to learn I am using an AES code that has 3 Rows and 4 columns in its Shift Rows. Although I know in AES we have 4 rows and 4 column block. Then why is it working, I am not able to understand that. Here is the code attached:

def shift_rows(s):
    s[1][0], s[1][1], s[1][2], s[1][3] = s[1][1], s[1][2], s[1][3], s[1][0]
    s[2][0], s[2][1], s[2][2], s[2][3] = s[2][2], s[2][3], s[2][0], s[2][1]
    s[3][0], s[3][1], s[3][2], s[3][3] = s[3][3], s[3][0], s[3][1], s[3][2]

Any guidance and information will be helpful.

Then why is it working, I am not able to understand that.

Because the ShiftRows operation in AES leaves the top row unchanged; your code does the same (by ignoring it).

As you might notice, the first row (Index 0) is never called. This makes sense because there is no change in the values contained in the first row by definition. This can be better understood by the visualization contained in the Wikipedia article about AES:

The code you shared only updates the values corresponding to the definition of AES, but does not create a new array. Therefore only the rows that are affected must be recomputed and overwritten, resulting in only updating 3 rows.