Feat: Ported sendCOMM method

This follows PR nasa#295 from the original NASA repository

Author: feimaomiao

Python3/src/xpc/__init__.py

@@ -424,6 +424,25 @@ def sendWYPT(self, op, points):
         else:
             buffer = struct.pack(("<4sxBB" + str(len(points)) + "f").encode(), b"WYPT", op, len(points), *points)
         self.sendUDP(buffer)
+    
+    def sendCOMM(self, comm):
+        '''Sets the specified datarefs to the specified values.
+            Args:
+            comm: Command to send.
+        '''
+        if comm == None:
+            raise ValueError("comm must be non-empty.")
+
+        buffer = struct.pack(b"<4sx", b"COMM")
+        if len(comm) == 0 or len(comm) > 255:
+            raise ValueError("comm must be a non-empty string less than 256 characters.")
+
+        # Pack message
+        fmt = "<B{0:d}s".format(len(comm))
+        buffer += struct.pack(fmt.encode(), len(comm), comm.encode())
+
+        # Send
+        self.sendUDP(buffer)
 
 
 class ViewType(object):