rowRange -- the range of row indices of a tableau

i1 : T = youngTableau(new Partition from {5,4,2,1,0,0}, new Partition from {2,2,2}, toList(1..6))

             ┌───┬───┬───┐
o1 =         │ 1 │ 2 │ 3 │
             ├───┼───┼───┘
             │ 4 │ 5 │    
             └───┴───┘    
                          
     ┌───┐                
     │ 6 │                
     └───┘                

o1 : YoungTableau

i2 : rowRange T

o2 = (0, 1, 2, 3)

o2 : Sequence

i3 : for i in rowRange T do print rowEntries(T,i)
{1, 2, 3}
{4, 5}
{}
{6}