I have still a problem with this function. I wrote in X_shortcut on the end (X_shortcut) instead (X) but I didn’t change anything.
If your rest of the code is correct, then I guess you are working on the old version of the assignment. Course staff has updated this assignment in which you don’t need to mention training=training for exercises 1 and 2. If you see that you have to specify this parameter, it’s time to get a fresh copy of your notebook as described here.
I do not have specify this parameter, and my identity_block function work correct 
Then please compare your code with the instructions. It is normal to make mistakes on the first attempt but rereading the instructions will help.
Yes, as Saif implies, this assignment is an exercise in very careful proofreading. There are lots of details that you have to get right. But also notice that in your incorrect output, every row of the 4 shown is exactly the same. None of the rows match in the “expected” output. So that is some kind of clue about the nature of the mistake(s).