Replaces and moves invert, refs #1731

doc/Type/Any.pod6

@@ -973,15 +973,32 @@ Defined as:
     multi method antipairs(Any:U:)
     multi method antipairs(Any:D:)
 
-Converts the invocant to a L<List|/type/List> via the C<list> method and returns the result of
-L<List.antipairs|/type/List#routine_antipairs> on it.
-Returns an empty L<List|/type/List> if the invocant is undefined:
+Converts the invocant to a L<List|/type/List> via the C<list> method and returns
+the result of L<List.antipairs|/type/List#routine_antipairs> on it. Returns an
+empty L<List|/type/List> if the invocant is undefined:
 
     my $a;
     say $a.antipairs;      # OUTPUT: «()»
     $a = Any.new;
     say $a.antipairs;      # OUTPUT: «(Any.new => 0)»
 
+=head2 method invert
+
+Defined as:
+
+    multi method invert(Any:U:)
+    multi method invert(Any:D:)
+
+Applied to a type object will return an empty list; applied to an object will
+convert it to a list and apply L<C<List.invert>|/type/List#routine_invert> to
+it, that is, interchange key with value in every Pair. The resulting list needs
+to be a list of C<Pair>s.
+
+    "aaabbcccc".comb.Bag.invert.say; # OUTPUT: «(4 => c 3 => a 2 => b)␤»
+
+In this case, a C<Bag> can be converted to a list of C<Pair>s. If the result of
+converting the object to a list is not a list of pairs, the method will fail.
+
 
 =head2 method kv
 
@@ -1131,16 +1148,6 @@ details.
 
     say Any.nl-out; # OUTPUT: «␤␤»
 
-=head2 method invert
-
-Defined as:
-
-    method invert(--> List)
-
-Returns an empty List.
-
-    say Any.invert; # OUTPUT: «()␤»
-
 =head2 method combinations
 
 Defined as: