code: def automated_readability_index(doc: Doc) -> float:
      """
      Readability test for English-language texts, particularly for technical writing,
      whose value estimates the U.S. grade level required to understand a text.
      Similar to several other tests (e.g. :func:`flesch_kincaid_grade_level()`),
      but uses characters per word instead of syllables like :func:`coleman_liau_index()`.
  
      Higher value => more difficult text.
  
      Args:
          doc
  
      References:
          https://en.wikipedia.org/wiki/Automated_readability_index
      """
      words = tuple(utils.get_words(doc))
      n_sents = basics.n_sents(doc)
      n_words = basics.n_words(words)
      n_chars = basics.n_chars(words)
      return (
          (4.71 * n_chars / n_words) + (0.5 * n_words / n_sents) - 21.43
      )
  
file_path: textacy/src/textacy/text_stats/readability.py
imports: import logging
  import math
  import statistics
  from typing import Optional
  from spacy.tokens import Doc
  from ..None import errors
  from .None import basics, utils
label_desc: Use image node_id 1 for calling a global function with example usage: automated_readability_index(doc) and returns: unknown