class_docstr: Normalized compression distance (NCD)
  
  https://articles.orsinium.dev/other/ncd/
  https://en.wikipedia.org/wiki/Normalized_compression_distance#Normalized_compression_distance
code: def _compress(self, data: str) -> Any:
      raise NotImplementedError
  
imports: from __future__ import annotations
  import codecs
  import math
  from collections import Counter
  from fractions import Fraction
  from itertools import groupby, permutations
  from typing import Any, Sequence, TypeVar
  from .base import Base
label_desc: Use image node_id 4 for calling the _NCDBase obj's underlying member method code with example usage: obj._compress(data) without return types