class_docstr: A data frame class, with only the methods required by the interchange
  protocol defined.
  
  A "data frame" represents an ordered collection of named columns.
  A column's "name" must be a unique string.
  Columns may be accessed by name or by position.
  
  This could be a public data frame class, or an object with the methods and
  attributes defined on this DataFrame class could be returned from the
  ``__dataframe__`` method of a public data frame class in a library adhering
  to the dataframe interchange protocol specification.
docstr: Return an iterator yielding the column names.
docstr_tok: ["Return","an","iterator","yielding","the","column","names","."]
code: def column_names(self) -> Iterable[str]:
      """
      Return an iterator yielding the column names.
      """
      pass
  
file_path: altair/altair/utils/_dfi_types.py
imports: import enum
  from typing import Any, Iterable, Optional, Tuple, Protocol
label_desc: Use image node_id 2 for calling the DataFrame obj's underlying member method code with example usage: obj.column_names() without return types