code: def onShortcutUnindentWithBackspace(self):
          
          assert self._qpart.textBeforeCursor().endswith(self.text())
  
          charsToRemove = len(self._qpart.textBeforeCursor()) % len(self.text())
          if charsToRemove == 0:
              charsToRemove = len(self.text())
  
          cursor = self._qpart.textCursor()
          cursor.setPosition(cursor.position() - charsToRemove, QTextCursor.KeepAnchor)
          cursor.removeSelectedText()
docs: Backspace pressed, unindent