code: def select(self, columns: List[str]) -> "pandas.DataFrame":
      if not all(isinstance(col, str) for col in columns):
          raise ValueError(
              "Columns must be a list of column name strings when aggregating on "
              f"Pandas blocks, but got: {columns}."
          )
      return self._table[columns]
  
imports: import collections
  import heapq
  from typing import TYPE_CHECKING, Any, Callable, Dict, Iterator, List, Optional, Tuple, TypeVar, Union
  import numpy
  from ray.air.constants import TENSOR_COLUMN_NAME
  from ray.data._internal.table_block import TableBlockAccessor, TableBlockBuilder
  from ray.data._internal.util import find_partitions
  from ray.data.block import Block, BlockAccessor, BlockExecStats, BlockMetadata, KeyType, U
  from ray.data.context import DataContext
  from ray.data.row import TableRow
label_desc: Use image node_id 7 for calling the PandasBlockAccessor obj's underlying member method code with example usage: obj.select(columns) and returns: self