code: def get_column(self, col):
          
          logging.info('getting %s' % col)
          vals = []
          for f in self.files:
              d = FileData(f, group=self.group, columnlist=self.columns,
                           filter_func=self.filter_func)
              vals.append(d.get_column(col))
              # Close each file since h5py has an upper limit on the number of
              # open file objects (approx. 1000)
              d.close()
          logging.info('- got %i values' % sum(len(v) for v in vals))
          return np.concatenate(vals)
docs: Loop over files getting the requested dataset values from each
  
          Parameters
          ----------
          col : string
              Name of the dataset to be returned
  
          Returns
          -------
          numpy array
              Values from the dataset, filtered if requested and
              concatenated in order of file list