code: def isabs(self, path):
          
          if self.filesystem.is_windows_fs:
              path = self.splitdrive(path)[1]
          path = make_string_path(path)
          sep = self.filesystem._path_separator(path)
          altsep = self.filesystem._alternative_path_separator(path)
          if self.filesystem.is_windows_fs:
              return len(path) > 0 and path[:1] in (sep, altsep)
          else:
              return (path.startswith(sep) or
                      altsep is not None and path.startswith(altsep))
docs: Return True if path is an absolute pathname.