code: def _update_history(self):
          
          version = self.data['new_version']
          history = self.vcs.history_file()
          if not history:
              logger.warn("No history file found")
              return
          history_lines = open(history).read().split('\n')
          headings = utils.extract_headings_from_history(history_lines)
          if not len(headings):
              logger.warn("No detectable existing version headings in the "
                          "history file.")
              inject_location = 0
              underline_char = '-'
          else:
              first = headings[0]
              inject_location = first['line']
              underline_line = first['line'] + 1
              try:
                  underline_char = history_lines[underline_line][0]
              except IndexError:
                  logger.debug("No character on line below header.")
                  underline_char = '-'
          header = '%s (unreleased)' % version
          inject = [header,
                    underline_char * len(header),
                    '',
                    self.data['nothing_changed_yet'],
                    '',
                    '']
          history_lines[inject_location:inject_location] = inject
          contents = '\n'.join(history_lines)
          open(history, 'w').write(contents)
          logger.info("Injected new section into the history: %r", header)
docs: Update the history file