code: def create_time_labels(self):
          
          min_time = int(floor(min(self.data.axis['time'][0])))
          max_time = int(ceil(max(self.data.axis['time'][0])))
          n_time_labels = self.parent.value('n_time_labels')
  
          self.idx_time = []
          self.time_pos = []
          for one_time in linspace(min_time, max_time, n_time_labels):
              x_label = (self.data.start_time +
                         timedelta(seconds=one_time)).strftime('%H:%M:%S')
              item = QGraphicsSimpleTextItem(x_label)
              item.setFlag(QGraphicsItem.ItemIgnoresTransformations)
              self.idx_time.append(item)
              self.time_pos.append(QPointF(one_time,
                                           len(self.idx_label) *
                                           self.parent.value('y_distance')))
docs: Create the time labels, but don't plot them yet.
  
          Notes
          -----
          It's necessary to have the height of the time labels, so that we can
          adjust the main scene.
  
          Not very robust, because it uses seconds as integers.