cleanString (x:y:z) = 
    if 
        x == y
    then
        cleanString( y : z)
    else
       x : cleanString (y:z)
cleanString (x:y:z) = 
    if 
        x == y
    then
        cleanString( y : z)
    else
       x : cleanString (y:z)
cleanString (x:y:z) = 
    if 
        x == y
    then
        cleanString( y : z)
    else
       x : cleanString (y:z)