docs: def pmid(self,
               pmid=None,
               entry_name=None,
               first=None,
               last=None,
               volume=None,
               name=None,
               date=None,
               title=None,
               limit=None,
               as_df=False
               ):
          """Method to query :class:`.models.Pmid` objects in database
  
          :param pmid: PubMed identifier(s)
          :type pmid: int or tuple(int) or None
  
          :param entry_name: name(s) in :class:`.models.Entry`
          :type entry_name: str or tuple(str) or None
  
          :param first: first page(s)
          :type first: str or tuple(str) or None
  
          :param last: last page(s)
          :type last: str or tuple(str) or None
  
          :param volume: volume(s)
          :type volume: int or tuple(int) or None
  
          :param name: name(s) of journal
          :type name: str or tuple(str) or None
  
          :param date: publication year(s)
          :type date: int or tuple(int) or None
  
          :param title: title(s) of publication
          :type title: str or tuple(str) or None
  
          :param limit:
              - if `isinstance(limit,int)==True` -> limit
              - if `isinstance(limit,tuple)==True` -> format:= tuple(page_number, results_per_page)
              - if limit == None -> all results
          :type limit: int or tuple(int) or None
  
          :param bool as_df: if `True` results are returned as :class:`pandas.DataFrame`
  
          :return:
              - if `as_df == False` -> list(:class:`.models.Pmid`)
              - if `as_df == True`  -> :class:`pandas.DataFrame`
          :rtype: list(:class:`.models.Pmid`) or :class:`pandas.DataFrame`
          """
          q = self.session.query(models.Pmid)
  
          model_queries_config = (
              (pmid, models.Pmid.pmid),
              (last, models.Pmid.last),
              (first, models.Pmid.first),
              (volume, models.Pmid.volume),
              (name, models.Pmid.name),
              (date, models.Pmid.date),
              (title, models.Pmid.title)
          )
          q = self.get_model_queries(q, model_queries_config)
  
          q = self.get_many_to_many_queries(q, ((entry_name, models.Pmid.entries, models.Entry.name),))
  
          return self._limit_and_df(q, limit, as_df)