+=head2 C<begin>
+
+=cut
+
+sub begin {
+ my $set = shift;
+
+ my @points = $set->points;
+ return undef unless @points;
+
+ $points[0]->begin;
+}
+
+=head2 C<end>
+
+=cut
+
+sub end {
+ my $set = shift;
+
+ my @points = $set->points;
+ return undef unless @points;
+
+ $points[-1]->end;
+}
+