class_docstr: ISRI Arabic stemmer based on algorithm: Arabic Stemming without a root dictionary.
  Information Science Research Institute. University of Nevada, Las Vegas, USA.
  
  A few minor modifications have been made to ISRI basic algorithm.
  See the source code of this module for more information.
  
  isri.stem(token) returns Arabic root for the given token.
  
  The ISRI Stemmer requires that all tokens have Unicode string types.
  If you use Python IDLE on Arabic Windows you have to decode text first
  using Arabic '1256' coding.
class_docstr_tok: ["ISRI","Arabic","stemmer","based","on","algorithm",":","Arabic","Stemming","without","a","root","dictionary",".","Information","Science","Research","Institute",".","University","of","Nevada",",","Las","Vegas",",","USA",".","A","few","minor","modifications","have","been","made","to","ISRI","basic","algorithm",".","See","the","source","code","of","this","module","for","more","information",".","isri.stem","(","token",")","returns","Arabic","root","for","the","given","token",".","The","ISRI","Stemmer","requires","that","all","tokens","have","Unicode","string","types",".","If","you","use","Python","IDLE","on","Arabic","Windows","you","have","to","decode","text","first","using","Arabic","'1256","'","coding","."]
docstr: process length six patterns and extract length three roots
docstr_tok: ["process","length","six","patterns","and","extract","length","three","roots"]
code: def pro_w6(self, word):
      """process length six patterns and extract length three roots"""
      if word.startswith("\u0627\u0633\u062a") or word.startswith(
          "\u0645\u0633\u062a"
      ):  # مستفعل - استفعل
          word = word[3:]
      elif (
          word[0] == "\u0645"
          and word[3] == "\u0627"
          and word[5] == "\u0629"
      ):  # مفعالة
          word = word[1:3] + word[4]
      elif (
          word[0] == "\u0627"
          and word[2] == "\u062a"
          and word[4] == "\u0627"
      ):  # افتعال
          word = word[1] + word[3] + word[5]
      elif (
          word[0] == "\u0627"
          and word[3] == "\u0648"
          and word[2] == word[4]
      ):  # افعوعل
          word = word[1] + word[4:]
      elif (
          word[0] == "\u062a"
          and word[2] == "\u0627"
          and word[4] == "\u064a"
      ):  # تفاعيل   new pattern
          word = word[1] + word[3] + word[5]
      else:
          word = self.suf1(word)  # do - normalize short sufix
          if len(word) == 6:
              word = self.pre1(word)  # do - normalize short prefix
      return word
  
file_path: nltk/nltk/stem/isri.py
imports: import re
  from nltk.stem.api import StemmerI
label_desc: Use image node_id 11 for calling the ISRIStemmer obj's underlying member method code with example usage: obj.pro_w6(word) and returns: word