docs: def _convert(self, block_node):
          """
          Convert a VEX block to an AIL block.
  
          :param block_node:  A BlockNode instance.
          :return:            An converted AIL block.
          :rtype:             ailment.Block
          """
  
          if not type(block_node) is BlockNode:
              return block_node
  
          block = self.project.factory.block(block_node.addr, block_node.size)
  
          ail_block = ailment.IRSBConverter.convert(block.vex, self._ail_manager)
          return ail_block