docs: def prepopulate(self):
          """
          Creates a database file (if it doesn't exist, writes each data point's path, real_id into it)
  
          Parameters
          ----------
          self
  
          Returns
          -------
          None
          """
          if self._prepopulated is False:
              engine = create_engine('sqlite:////' + self.dbpath)
              self._db_base.metadata.create_all(engine)
              self._prepopulated = True
              session_cl = sessionmaker(bind=engine)
              session = session_cl()
  
              for (dirpath, dirnames, filenames) in walk(self.path_to_set):
                  for f_name in filenames:
                      datapoint = self._set_object(real_id=cutoff_filename(self.file_prefix, self.file_suffix, f_name),
                                                   path=f_name, features=None)
                      session.add(datapoint)
                      self.points_amt += 1
              session.commit()
              session.close()
          return None