First attempt

examples/07_python_network/example.py

@@ -0,0 +1,32 @@
+"""
+07_python_network — hello pipeline with a Python node in the middle.
+
+Graph:
+  [ProduceNode] --int--> [py_double] --int--> [PrintItNode]
+
+ProduceNode and PrintItNode are C++ nodes wrapped in VariantNodeWrapper.
+py_double is a pure Python callable — doubles its input using Python arithmetic.
+"""
+
+import sys
+import time
+sys.path.insert(0, "build/python")
+
+import kpn_python as kpn
+
+def py_double(x: int) -> int:
+    return x * 2
+
+net = kpn.Network()
+
+net.add("src",  kpn.make_produce())
+net.add_node("dbl", py_double, inputs=["int"], outputs=["int"])
+net.add("sink", kpn.make_print_it())
+
+net.connect("src",  0, "dbl",  0)
+net.connect("dbl",  0, "sink", 0)
+
+net.build()
+net.start()
+time.sleep(0.1)
+net.stop()