code: def check_license(self):
          
  
          opts = self.distribution.get_option_dict('metadata')
  
          # ignore the source of the value
          _, license_file = opts.get('license_file', (None, None))
  
          if license_file is None:
              log.debug("'license_file' option was not specified")
              return
  
          if not os.path.exists(license_file):
              log.warn("warning: Failed to find the configured license file '%s'",
                      license_file)
              return
  
          self.filelist.append(license_file)
docs: Checks if license_file' is configured and adds it to
          'self.filelist' if the value contains a valid path.