  
          for index, select_col in enumerate(self.query.select):
              lhs_sql, lhs_params = self.compile(select_col)
              rhs = "%s.%s" % (qn(alias), qn2(columns[index]))
              self.query.where.add(RawSQL("%s = %s" % (lhs_sql, rhs), lhs_params), "AND")
  
          sql, params = self.as_sql()
          return "EXISTS (%s)" % sql, params
  
      def explain_query(self):
 
</s> remove         w = WhereNode(children=[NothingNode()], connector="OR")
 </s> add         w = WhereNode(children=[NothingNode()], connector=OR) </s> remove         self.assertEqual(kwargs, {"_connector": "XOR"})
 </s> add         self.assertEqual(kwargs, {"_connector": Q.XOR}) </s> remove         self.assertEqual(kwargs, {"_connector": "OR"})
 </s> add         self.assertEqual(kwargs, {"_connector": Q.OR}) </s> remove         w = WhereNode(children=[NothingNode(), self.DummyNode()], connector="OR")
 </s> add         w = WhereNode(children=[NothingNode(), self.DummyNode()], connector=OR) </s> remove         w.connector = "OR"
 </s> add         w.connector = OR
            self.query.where.add(RawSQL("%s = %s" % (lhs_sql, rhs), lhs_params), AND)
  
          for index, select_col in enumerate(self.query.select):
              lhs_sql, lhs_params = self.compile(select_col)
              rhs = "%s.%s" % (qn(alias), qn2(columns[index]))
            self.query.where.add(RawSQL("%s = %s" % (lhs_sql, rhs), lhs_params), AND)
  
          sql, params = self.as_sql()
          return "EXISTS (%s)" % sql, params
  
      def explain_query(self):
keep keep keep keep replace keep keep keep keep keep
 Used AND, OR, XOR constants instead of hard-coded values. 
django/db/models/sql/compiler.py