feat: Don't print an id for orphan values

examples/python_optimization/python_optimization.ipynb

@@ -337,19 +337,19 @@
       "jeff v0\n",
       "\n",
       "[entry] func @main(int1) -> ():\n",
-      "  in : %4397829072:int1\n",
-      "    %4402776464:qubit = qubit.alloc \n",
-      "    %4402736208:qubit = qubit.gate %4402776464:qubit (h)\n",
-      "    %4402834256:int1 = int.not %4397829072:int1\n",
-      "    %4404055888:qubit = scf.switch %4402834256:int1, %4402736208:qubit \n",
+      "  in : :int1\n",
+      "    :qubit = qubit.alloc \n",
+      "    :qubit = qubit.gate :qubit (h)\n",
+      "    :int1 = int.not :int1\n",
+      "    :qubit = scf.switch :int1, :qubit \n",
       "      case 0:\n",
-      "        in : %4404309008:qubit\n",
-      "          %4404304208:qubit = qubit.gate %4404309008:qubit (h)\n",
-      "        out: %4404304208:qubit\n",
+      "        in : :qubit\n",
+      "          :qubit = qubit.gate :qubit (h)\n",
+      "        out: :qubit\n",
       "      default:\n",
-      "        in : %4404302800:qubit\n",
-      "        out: %4404302800:qubit\n",
-      "    qubit.free %4404055888:qubit\n",
+      "        in : :qubit\n",
+      "        out: :qubit\n",
+      "    qubit.free :qubit\n",
       "  out:\n",
       "\n"
      ]
@@ -399,8 +399,7 @@
    "metadata": {},
    "source": [
     "As we can see we re-created the same program as the one we loaded originally, the only difference\n",
-    "is that program values have some random-looking values assigned to them. This is the Python id of\n",
-    "the value object, which is a local property. To obtain the nicer print-out from before with globally\n",
+    "is that program values do not have an id assigned to them. To obtain the nicer print-out from before with globally\n",
     "assigned labels for the value, we can encode the program into cap'n proto and generate a value\n",
     "table in the process:"
    ]

impl/py/src/jeff/__init__.py

@@ -283,16 +283,20 @@ def type(self):
     # convenience methods
 
     @property
-    def id(self) -> int:
+    def id(self) -> int | None:
         if self._val_idx is not None:
             return self._val_idx
 
-        return id(self)
+        return None
 
     # Python integration
 
     def __str__(self):
-        return f"%{self.id}:{self.type}"
+        match self.id:
+            case None:
+                return f":{self.type}"
+            case _:
+                return f"%{self.id}:{self.type}"
 
     def __eq__(self, other):
         if not isinstance(other, JeffValue):