code: def read_prologue(self):
          
  
          with open(self.filename, "rb") as fp_:
              fp_.seek(self.mda['total_header_length'])
              data = np.fromfile(fp_, dtype=hrit_prologue, count=1)
              self.prologue.update(recarray2dict(data))
              try:
                  impf = np.fromfile(fp_, dtype=impf_configuration, count=1)[0]
              except IndexError:
                  logger.info('No IMPF configuration field found in prologue.')
              else:
                  self.prologue.update(recarray2dict(impf))
docs: Read the prologue metadata.