Goal:
    A : Type  B : Type  n : nat  f : A → B  l : list A
  ============================
   (#|skipn n (map f l)| = #|skipn n l|)


DEBUG:Going to execute:
<coq-core.plugins.ssreflect::ssrrewrite@0> $1 $2

File "./theories/MCList.v", line 663, characters 15-32:
Warning: Notation List.skipn_length is deprecated since 8.20.
Use length_skipn instead.
[deprecated-syntactic-definition-since-8.20,deprecated-since-8.20,deprecated-syntactic-definition,deprecated,default]
File "./theories/MCList.v", line 663, characters 15-32:
Warning: Notation List.skipn_length is deprecated since 8.20.
Use length_skipn instead.
[deprecated-syntactic-definition-since-8.20,deprecated-since-8.20,deprecated-syntactic-definition,deprecated,default]
File "./theories/MCList.v", line 663, characters 15-32:
Warning: Notation List.skipn_length is deprecated since 8.20.
Use length_skipn instead.
[deprecated-syntactic-definition-since-8.20,deprecated-since-8.20,deprecated-syntactic-definition,deprecated,default]
File "./theories/MCList.v", line 663, characters 15-32:
Warning: Notation List.skipn_length is deprecated since 8.20.
Use length_skipn instead.
[deprecated-syntactic-definition-since-8.20,deprecated-since-8.20,deprecated-syntactic-definition,deprecated,default]