code: def createEditor(self, parent, option, index):
          
          editor = BigIntSpinbox(parent)
          try:
              editor.setMinimum(self.minimum)
              editor.setMaximum(self.maximum)
              editor.setSingleStep(self.singleStep)
          except TypeError as err:
              # initiate the editor with default values
              pass
          return editor
docs: Returns the widget used to edit the item specified by index for editing. The parent widget and style option are used to control how the editor widget appears.
  
          Args:
              parent (QWidget): parent widget.
              option (QStyleOptionViewItem): controls how editor widget appears.
              index (QModelIndex): model data index.