docstr: Get word count by doc url
docstr_tok: ["Get","word","count","by","doc","url"]
code: def get_doc_word_counters(self, dataset):
      """Get word count by doc url"""
      data = self._get_doc_sents(dataset)
      doc_word_counters = {}
      for doc, sents in data.items():
          tags = [s.rows for s in sents]
          tags = [t for sublist in tags for t in sublist]
          words = [t[0].lower() for t in tags]
          doc_word_counters[doc] = Counter(words)
      return doc_word_counters
  
imports: import math
  from underthesea.dictionary import Dictionary
  from collections import Counter, defaultdict
  from underthesea.utils import logger
  from datetime import date, timedelta
  import pandas
label_desc: Use image node_id 4 for calling the UDAnalyzer obj's underlying member method code with example usage: obj.get_doc_word_counters(dataset) and returns: doc_word_counters