code: def calculateBoundingRect(self, nodes):
          
          out = QRectF()
          for node in nodes:
              rect = node.rect()
              pos = node.pos()
              
              bounding = QRectF(pos.x(), pos.y(), rect.width(), rect.height())
              out = out.united(bounding)
          
          return out
docs: Returns the bounding rectangle for the inputed nodes.
          
          :param      nodes | [<XNode>, ..]