docs: def _expand_filename(self, line):
          """expands the filename if there is a . as leading path"""
          # expand .
          newline = line
          path = os.getcwd()
          if newline.startswith("."):
              newline = newline.replace(".", path, 1)
          # expand ~
          newline = os.path.expanduser(newline)
          return newline