Recursion Removal Rules


append... goes into flatll(xs,<DUMMY,0>)
↓
flatll(x,<acc,num>) = case x of 
    nil         -> accnil
    Cons[x1,xs] -> flatll(xs,<DUMMY
append(x1,DUMMY,<acc,num>),2>)  
finally
↓
flatll(x,<acc,num>) = case x of 
    nil         -> accnil
    Cons[x1,xs] -> 
flatll(xs,<append(x1,DUMMY,<acc,num>),2>)