diff -r 845ca626db09 -r 56e7f4a11046 plcopen/plcopen.py
--- a/plcopen/plcopen.py	Thu Aug 17 09:55:39 2017 +0300
+++ b/plcopen/plcopen.py	Thu Aug 17 10:04:24 2017 +0300
@@ -1678,7 +1678,7 @@
                 for variable in instance.inputVariables.getvariable():
                     connections = variable.connectionPointIn.getconnections()
                     if connections and len(connections) == 1:
-                        if (self.checkedBlocksDict.has_key(connections[0].getrefLocalId()) == False):
+                        if not self.checkedBlocksDict.has_key(connections[0].getrefLocalId()):
                             self.compileelementExecutionOrder(connections[0])
                 if instance.getexecutionOrderId() == 0:
                     instance.setexecutionOrderId(self.getnewExecutionOrderId())