chore: add example for ZMQ (#33)

examples/example_zmq.py

@@ -0,0 +1,37 @@
+import sys
+import zmq
+
+
+def main() -> None:
+    if len(sys.argv) < 2:
+        print("Usage: python3 ./example_zmq.py <connect_to> [topic topic ...]")
+        sys.exit(1)
+
+    connect_to = sys.argv[1]
+    topics = sys.argv[2:]
+    ctx = zmq.Context()
+    s = ctx.socket(zmq.SUB)
+    s.connect(connect_to)
+
+    # manage subscriptions
+    if not topics:
+        print("Receiving messages on ALL topics...")
+        s.setsockopt(zmq.SUBSCRIBE, b"")
+    else:
+        print(f"Receiving messages on topics: {topics} ...")
+        for t in topics:
+            s.setsockopt(zmq.SUBSCRIBE, bytes.fromhex(t))
+    print
+    try:
+        while True:
+            msg = s.recv_multipart()
+            hex_string = [b.hex() for b in msg]
+            print("msg: {}".format(hex_string))
+
+    except KeyboardInterrupt:
+        pass
+    print("Done.")
+
+
+if __name__ == "__main__":
+    main()