code: def _sanity_check_query_root_block(ir_blocks):
      
      if not isinstance(ir_blocks[0], QueryRoot):
          raise AssertionError(u'The first block was not QueryRoot: {}'.format(ir_blocks))
      for block in ir_blocks[1:]:
          if isinstance(block, QueryRoot):
              raise AssertionError(u'Found QueryRoot after the first block: {}'.format(ir_blocks))
docs: Assert that QueryRoot is always the first block, and only the first block.