Initial commit of Python queries and QL libraries.

python/ql/src/Statements/UnusedExceptionObject.ql

@@ -0,0 +1,19 @@
+/**
+ * @name Unused exception object
+ * @description An exception object is created, but is not used.
+ * @kind problem
+ * @tags reliability
+ *       maintainability
+ * @problem.severity error
+ * @sub-severity low
+ * @precision very-high
+ * @id py/unused-exception-object
+ */
+
+import python
+
+from Call call, ClassObject ex
+where call.getFunc().refersTo(ex) and ex.getAnImproperSuperType() = theExceptionType()
+and exists(ExprStmt s | s.getValue() = call)
+
+select call, "Instantiating an exception, but not raising it, has no effect"