Initial line:       W,X,Y,Z
Negated class:      W,X,YZ
Negative assertion: W,X,YZ
----------------------------------------
Initial line:       W,X,YZ
Negated class:      W,XYZ
Negative assertion: W,XYZ
----------------------------------------
Initial line:       W,XYZ
Negated class:      WXYZ
Negative assertion: WXYZ
----------------------------------------
Initial line:       WXYZ
Negated class:      WXYZ
Negative assertion: WXYZ
----------------------------------------