code: def indent(self):
          
  
          cursor = self.textCursor()
          if not cursor.hasSelection():
              cursor.insertText(self.__indent_marker)
          else:
              block = self.document().findBlock(cursor.selectionStart())
              while True:
                  block_cursor = self.textCursor()
                  block_cursor.setPosition(block.position())
                  block_cursor.insertText(self.__indent_marker)
                  if block.contains(cursor.selectionEnd()):
                      break
                  block = block.next()
          return True
docs: Indents the document text under cursor.
  
          :return: Method success.
          :rtype: bool