Merge pull request #3183 from dumarchie/#3163

Improve some Seq method definitions

Author: dumarchie

doc/Type/Seq.pod6

@@ -76,18 +76,19 @@ Creates a new C<Seq> object from the iterator passed as the single argument.
 
     method iterator(Seq:D: --> Iterator:D)
 
-Returns the underlying iterator, and marks the invocant as consumed.
-If called on an already consumed sequence, throws an error of type
-L<X::Seq::Consumed|/type/X::Seq::Consumed>.
+If the C<Seq> is not cached, returns the underlying iterator and marks
+the invocant as consumed. If called on an already consumed sequence,
+throws an error of type L<X::Seq::Consumed|/type/X::Seq::Consumed>.
+
+Otherwise returns an iterator over the cached list.
 
 =head2 method is-lazy
 
     method is-lazy(Seq:D: --> Bool:D)
 
-Returns C<True> if and only if the underlying iterator guarantees lazy
-evaluation and has not been completely evaluated. If called on an
-already consumed sequence, throws an error of type
-L<X::Seq::Consumed|/type/X::Seq::Consumed>.
+Returns C<True> if and only if the underlying iterator or cached list
+considers itself lazy. If called on an already consumed sequence, throws
+an error of type L<X::Seq::Consumed|/type/X::Seq::Consumed>.
 
 =head2 method elems
 
@@ -98,7 +99,7 @@ predicted, the C<Seq> is cached and evaluated till the end.
 
 Because an infinite sequence cannot be evaluated till the end, such a
 sequence I<should> be declared lazy. Calling C<.elems> on a lazy C<Seq>
-throws an error of type L<X::Cannot::Lazy|/type/X::Cannot::Lazy>.
+L<fails|/routine/fail> with L<X::Cannot::Lazy|/type/X::Cannot::Lazy>.
 
 =head2 method eager