docs: def query( self ):
          """
          Returns the query for this item by joining together its children, 
          or building its data.
          
          :return     <Query> || <QueryCompound>
          """
          if ( self.childCount() ):
              q = Q()
              for i in range(self.childCount()):
                  q &= self.child(i).query()
              return q
          else:
              op_name = projex.text.classname(self.text(2))
              q = Q(nativestring(self.text(1)))
              q.setOperatorType(Q.Op[op_name])
              q.setValueString(nativestring(self.text(3)))
              return q