title: QTreeView and using QStandardModel to append items
body: <p>I using <code>QStandardItemModel</code> to maintain <code>QTreeView</code>, and how can I modify or delete the red circle in the images below .
  Thanks.</p>
  
  <pre class="lang-py prettyprint-override"><code>from PySide2 import QtCore,QtGui
  from PySide2.QtGui import QStandardItemModel
  import pandas as pd
  
  class PrjTreeModel(QStandardItemModel):
  
      def __init__(self, parent=None):
          super(PrjTreeModel, self).__init__(parent)
          # self.items = data
          self.itmes = pd.DataFrame([['Hello','@TFF']],columns=['UserId','ProjectId']) 
          self.refreshItems()
  
      def refreshItems(self):
          prjId = self.itmes['ProjectId']
          child = ['RR','BB']
  
          for i,row in prjId.iteritems():
              parent = QtGui.QStandardItem(row)
              child1 = QtGui.QStandardItem(child[0])
              child2 = QtGui.QStandardItem(child[1])
              parent.appendRow(child1)
              parent.appendRow(child2)
              self.appendRow(parent)
      # def headerData(self, section, orientation, role=QtCore.Qt.DisplayRole):
      #     return self.itmes['UserId'][0]
  </code></pre>
  
  <p><a href="https://i.stack.imgur.com/bM0Vd.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/bM0Vd.jpg" alt="no"></a></p>