Improve BagHash.new examples(Close #1629)

#1629

Author: tisonkun

doc/Type/BagHash.pod6

@@ -50,10 +50,18 @@ say $breakfast.kxxv.sort;  # OUTPUT: «eggs sausage sausage spam spam spam spam
 C<BagHash>es can be composed using C<BagHash.new>.  Any positional parameters,
 regardless of their type, become elements of the bag:
 
-    my $n = BagHash.new: "a" => 0, "b" => 1, "c" => 2, "c" => 2;
-    say $n.keys.perl;        # OUTPUT: «(:c(2), :b(1), :a(0)).Seq␤»
-    say $n.keys.map(&WHAT);  # OUTPUT: «((Pair) (Pair) (Pair))␤»
-    say $n.values.perl;      # OUTPUT: «(2, 1, 1).Seq␤»
+    my $n = BagHash.new: "a", "b", "c", "c";
+    say $n.perl;             # OUTPUT: «("b"=>1,"a"=>1,"c"=>2).BagHash␤» 
+    say $n.keys.perl;        # OUTPUT: «("b", "a", "c").Seq␤»
+    say $n.values.perl;      # OUTPUT: «(1, 1, 2).Seq␤»
+
+Besides, C<BagHash.new-from-pairs> can create a C<BagHash> with items and their
+occurrences.
+
+    my $n = BagHash.new-from-pairs: "a" => 0, "b" => 1, "c" => 2, "c" => 2;
+    say $n.perl;             # OUTPUT: «("b"=>1,"c"=>4).BagHash␤»
+    say $n.keys.perl;        # OUTPUT: «("b", "c").Seq␤»
+    say $n.values.perl;      # OUTPUT: «(1, 4).Seq␤»
 
 Alternatively, the C<.BagHash> coercer (or its functional form, C<BagHash()>)
 can be called on an existing object to coerce it to a C<BagHash>.  Its semantics
@@ -62,10 +70,10 @@ object in list context and creates a bag with the resulting items as elements,
 although for Hash-like objects or Pair items, only the keys become elements of
 the bag, and the (cumulative) values become the associated integer weights:
 
+    my $m = ("a", "b", "c", "c").BagHash;
     my $n = ("a" => 0, "b" => 1, "c" => 2, "c" => 2).BagHash;
-    say $n.keys.perl;        # OUTPUT: «("b", "c").Seq␤»
-    say $n.keys.map(&WHAT);  # OUTPUT: «((Str) (Str))␤»
-    say $n.values.perl;      # OUTPUT: «(1, 4).Seq␤»
+    say $m.perl;             # OUTPUT: «("b"=>1,"a"=>1,"c"=>2).BagHash␤»
+    say $n.perl;             # OUTPUT: «("b"=>1,"c"=>4).BagHash␤»
 
 =head1 Operators