At: tl append front 1 2 1
1. T: Type
2. l: T*
3. m: T*
4. u: T
5. v: T*
6. ||v|| > 0 
tl((v @ m)) = (tl(v) @ m)
7. ||u.v|| > 0
tl(((u.v) @ m)) = (tl((u.v)) @ m)
By:
RWH (AddrC [1] (RecUnfoldC `append`)) 0
THEN
Reduce 0
Generated subgoals:None
About: