Various missing item and hash contextualization bits.

src/builtins/Parcel.pir

@@ -53,6 +53,15 @@ A Parcel in item context becomes a Seq.
 .end
 
 
+=item hash()
+
+=cut
+
+.sub 'hash' :method
+    .tailcall 'hash'(self)
+.end
+
+
 =item iterator()
 
 Construct an iterator for the Parcel.

src/core/Mu.pm

@@ -1,6 +1,11 @@
 augment class Mu {
     method Bool { $.defined }
 
+    method item {
+        # This is overridden by non-items.
+        self;
+    }
+
     multi method notdef() { !self.defined; }
 
     multi method perl {

src/core/operators.pm

@@ -243,6 +243,16 @@ our sub WHAT(\$x) {
     $x.WHAT
 }
 
+our multi sub item(*@values) {
+    @values.Seq
+}
+our multi sub item(@values) {
+    @values.Seq
+}
+our multi sub item($item) {
+    $item
+}
+
 class Whatever { ... }
 
 # the magic one that handles stuff like