code: def schema(self) -> PandasBlockSchema:
      dtypes = self._table.dtypes
      schema = PandasBlockSchema(
          names=dtypes.index.tolist(), types=dtypes.values.tolist()
      )
      # Column names with non-str types of a pandas DataFrame is not
      # supported by Ray Dataset.
      if any(not isinstance(name, str) for name in schema.names):
          raise ValueError(
              "A Pandas DataFrame with column names of non-str types"
              " is not supported by Ray Dataset. Column names of this"
              f" DataFrame: {schema.names!r}."
          )
      return schema
  
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 9 for calling the PandasBlockAccessor obj's underlying member method code with example usage: obj.schema() and returns: schema