code: def _checked_columns(
      self, columns: Union[str, List[str]]
  ) -> List[Tuple[str, str]]:
      if isinstance(columns, str):
          columns = [columns]
      return [
          (col, self._dtype_map[col])
          for col in columns
          if (col in self._dtype_map)
      ]
  
imports: from typing import Generic, Union, Tuple, TypeVar, Dict, Iterator, Any, List
  from itertools import islice
  import numpy
  import logging
  from aim.sdk.tracker import STEP_HASH_FUNCTIONS
  from aim.storage.treeview import TreeView
  from aim.storage.arrayview import ArrayView
  from aim.storage.context import Context
  from aim.storage.hashing import hash_auto
  from typing import TYPE_CHECKING
label_desc: Use image node_id 3 for calling the SequenceData obj's underlying member method code with example usage: obj._checked_columns(columns) and returns: unknown