Empty new lines cause unhelpful/untrue diff in Mario in v4.0.0

[ivanharvard]

Printing any arbitrary amount of new lines at the end of the staff solution for Mario causes this error message:

:) mario.c exists
:) mario.c compiles
:) rejects a height of -1
:) rejects a height of 0
:( handles a height of 1 correctly
    expected: "#  #"
    actual:   "#  #"
    did you add too much trailing whitespace to the end of your pyramid?
:( handles a height of 2 correctly
    expected: "...#  ##"
    actual:   "...#  ##"
    did you add too much trailing whitespace to the end of your pyramid?
:( handles a height of 8 correctly
    expected: "...#####"
    actual:   "...#####"
    did you add too much trailing whitespace to the end of your pyramid?
:( rejects a height of -1, and then accepts a height of 2
    expected: "...#  ##"
    actual:   "...#  ##"
    did you add too much trailing whitespace to the end of your pyramid?
:) rejects a non-numeric height of "foo" 
:) rejects a non-numeric height of "" 

This is probably because of this line under check_pyramids() in problems/mario/less/__init__.py:

    output = [line for line in output.splitlines() if line != ""]

which removes all empty lines, including new lines, from the user's output, thus causing the diff to show equivalent expected and actual answers.

[SadhyarshiDubey]

where can i find the practice set 1