Using 0 for last Index for column and sheet
range r=0 //last column of active sheet
range r=1!0 //last column of 1st sheet,
range rsheet = 0! //last sheet
0!wcol(0)[0]= or 0!col(0)[0]=//last cell in last column of last sheet
layer -d 0 //Delete last sheet in active book or last layer in active graph