Rewrites tail closes #2631

doc/Type/List.pod6

@@ -489,19 +489,27 @@ Examples:
 
 Defined as:
 
-    method tail(List:D: Int(Cool) $number = 1 --> Seq:D)
+    multi method tail(List:D:)
+    multi method tail(List:D: $n --> Seq:D)
 
-Returns a L<Seq|/type/Seq> containing the B<last> NUMBER items of the list.
-Returns an empty C<Seq> if NUMBER <= 0.  Defaults to the last element if
-no NUMBER is specified. Throws an exception if the list is lazy.
+Returns a L<Seq|/type/Seq> containing the B<last> C<$n> items of the list.
+Returns an empty C<Seq> if C<$n> <= 0.  Defaults to the last element if
+no argument is specified. Throws an exception if the list is lazy.
 
 Examples:
 
 =for code
-say ^10 .tail(5);      # OUTPUT: «(5 6 7 8 9)␤»
-say ^∞ .tail(5);       # Cannot tail a lazy list
-say ^10 .tail;         # OUTPUT: «(9)␤»
-say ^∞ .tail;        # Cannot tail a lazy list
+say <a b c d e>.tail(*-3);# OUTPUT: «(d e)␤»
+say <a b c d e>.tail(2);  # OUTPUT: «(d e)␤»
+say <a b c d e>.tail;     # OUTPUT: «e␤»
+
+In the first case, C<$n> is taking the shape of a C<WhateverCode> to indicate
+the number of elements from the beginning that will be excluded. C<$n> can be
+either a Callable, in which case it will be called with the value C<0>, or
+anything else that can be converted to a number, in which case it will use
+that as the number of elements in the output C<Seq>.
+
+    say <a b c d e>.tail( { $_ - 2 } ); # OUTPUT: «(c d e)␤»
 
 =head2 routine categorize