| C.Meta (i,(m,l)) when k <= m+1 -> C.Meta (i,(m+n,l))
| C.Meta (_,(m,C.Irl l)) as t when k > l + m -> t
| C.Meta (i,(m,l)) ->
| C.Meta (i,(m,l)) when k <= m+1 -> C.Meta (i,(m+n,l))
| C.Meta (_,(m,C.Irl l)) as t when k > l + m -> t
| C.Meta (i,(m,l)) ->