Change IsAssigned method scoping

Author: ws-garcia

src/VBAexpressions.cls

@@ -5795,7 +5795,7 @@ err_Handler:
  IsArrayAllocated = False
 End Function
 
-Public Function IsAssigned(aVarName As String) As Boolean
+Private Function IsAssigned(aVarName As String) As Boolean
  IsAssigned = (LenB(P_SCOPE.VarValue(aVarName)) > 0)
 End Function