code: def smog_index(doc: Doc) -> float:
      """
      Readability test commonly used in medical writing and the healthcare industry,
      whose value estimates the number of years of education required to understand a text
      similar to :func:`flesch_kincaid_grade_level()` and intended as a substitute for
      :func:`gunning_fog_index()`.
  
      Higher value => more difficult text.
  
      Args:
          doc
  
      References:
          https://en.wikipedia.org/wiki/SMOG
      """
      n_sents = basics.n_sents(doc)
      n_polysyllable_words = basics.n_polysyllable_words(
          doc, lang=doc.lang_
      )
      if n_sents < 30:
          LOGGER.warning(
              "SMOG index may be unreliable for n_sents < 30"
          )
      return (
          1.0430 * math.sqrt(30 * n_polysyllable_words / n_sents)
      ) + 3.1291
  
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 11 for calling a global function with example usage: smog_index(doc) and returns: unknown