docs: def set_file_system(self, source_url=False, build_url=False):
          """Set the source file filesystem and/or build  file system"""
  
          assert isinstance(source_url, string_types) or source_url is None or source_url is False
          assert isinstance(build_url, string_types) or build_url is False
  
          if source_url:
              self._source_url = source_url
              self.dataset.config.library.source.url = self._source_url
              self._source_fs = None
  
          elif source_url is None:
              self._source_url = None
              self.dataset.config.library.source.url = self._source_url
              self._source_fs = None
  
          if build_url:
              self._build_url = build_url
              self.dataset.config.library.build.url = self._build_url
              self._build_fs = None
  
          self.dataset.commit()