First attempt

examples/08_python_subport/example.py

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+"""
+08_python_subport — tap a C++ node's output from Python using net.read().
+
+Graph:
+  [ProduceNode] --int--> [DoubleItNode] --int--> (tapped by net.read())
+
+The sink is Python: instead of connecting a PrintItNode, we call net.read()
+to pull values out of DoubleItNode's output directly into Python.
+We also demonstrate net.write() by injecting a value into DoubleItNode's input.
+"""
+
+import sys
+import time
+import threading
+sys.path.insert(0, "build/python")
+
+import kpn_python as kpn
+
+net = kpn.Network()
+
+net.add("src", kpn.make_produce())
+net.add("dbl", kpn.make_double_it())
+
+net.connect("src", 0, "dbl", 0)
+net.build()
+net.start()
+
+# Collect a few values from DoubleItNode's output via Python tap
+results = []
+for _ in range(5):
+    val = net.read("dbl", 0)
+    results.append(val)
+
+net.stop()
+
+print("values read from C++ DoubleItNode output:", results)
+assert all(v == 84 for v in results), f"expected all 84, got {results}"
+print("all correct (42 * 2 = 84)")