code: def is_integer_index(x) -> bool:
      """Check that the input is an integer pd.Index."""
      return isinstance(x, pd.Index) and pd.api.types.is_integer_dtype(
          x
      )
  
file_path: sktime/sktime/utils/validation/series.py
imports: from typing import Union
  import numpy
  import pandas
label_desc: Use image node_id 1 for calling a global function with example usage: is_integer_index(x) and returns: unknown