code: def load(self, data_file = None):
          
  
          if not data_file:
              data_file = ''
          elif data_file[-1] != '/':
              data_file += '/'
  
          if data_file[-6:] != self.lazy_folder:
              data_file += self.lazy_folder
          
          data_file += self.data_filename
  
          self.data = self._load(data_file)
          return self
docs: Loads a data file and sets it to self.data.
  
              Arguments:
              data_file -- The filename to load.