code: def promote_types(self, to_promote_blocks: list):
      for bid, block_type in to_promote_blocks:
          self._block_manager.blocks[bid] = self._block_manager.blocks[
              bid
          ].convert_block_type(block_type)
          for field_index in self._block_manager.blocks[
              bid
          ].field_indexes:
              self._schema_manager.set_field_type_by_offset(
                  field_index, block_type.value
              )
  
imports: import numpy
  from .schema_manager import SchemaManager
  from .block_manager import BlockManager
  from .block_manager import BlockType
  import pandas
  from ..entity import types
  from typing import Union, List, Tuple
  from ..conf.default_config import DATAFRAME_BLOCK_ROW_SIZE
label_desc: Use image node_id 27 for calling the DataManager obj's underlying member method code with example usage: obj.promote_types(to_promote_blocks) without return types