python intersection and set difference set

DEF the diff (listA, listB):
     # two ways of intersection of 
    RETA = [I for I in listA IF I in listB] 
    RETB = List (SET (listA) .intersection (SET (listB)))
     # Print ( "RETA IS: ", RETA) 
    # Print (" RETB IS: ", RETB) 
    # request and set 
    RETC = List (sET (listA) .union (sET (listB)))
     # Print (" retC1 IS: ", RETC) 
    # differencing set in B but not A, 
    Retd = List (sET (listB) .difference (sET (listA)))
     Print ( " Retd IS: " , Retd) 
    RETE= [i for i in listB if i not in listA]
    #print("retE is: ", retE)
listA = [1,2,3,4,5]
listB = [3,4,5,6,7]

diff(listA, listB)