
 The identity matrix :

              1/1  0/1  0/1       
       mID =  0/1  1/1  0/1          
              0/1  0/1  1/1        

 If you swap the row 0 and the row 2 of the identity matrix :

              0/1  0/1  1/1    > old row 2
       mID =  0/1  1/1  0/1           
              1/1  0/1  0/1    > old row 0

 And now if you multiply this matrix, 
 by a matrix mA for example :
    
              0/1  0/1  0/1       
        mA =  1/1  1/1  1/1          
              2/1  2/1  2/1   

 the rows of the matrix mA are also swapped.
     
              2/1  2/1   2/1        
  mID * mA =  1/1  1/1   1/1          
              0/1  0/1   0/1