libs/umqtt/simple.py: Add isconnected method.

Signed-off-by: lbuque <[email protected]>

Author: lbuque

m5stack/libs/umqtt/simple.py

@@ -121,6 +121,12 @@ def disconnect(self):
     def ping(self):
         self.sock.write(b"\xc0\0")
 
+    def isconnected(self):
+        try:
+            return self.sock.write(b"\xc0\0") == 2
+        except OSError:
+            return False
+
     def publish(self, topic, msg, retain=False, qos=0):
         pkt = bytearray(b"\x30\0\0\0")
         pkt[0] |= qos << 1 | retain