code: def imprint(self, path=None):
          
          if self.version is not None:
              with open(path or self.version_file, 'w') as h:
                  h.write(self.version + '\n')
          else:
              raise ValueError('Can not write null version to file.')
          return self
docs: Write the determined version, if any, to ``self.version_file`` or
             the path passed as an argument.