docs: def _strip_dollars_fast(text):
      """
      Replace `$$` with `$`. raise immediately
      if `$` starting an interpolated expression is found.
      @param text: the source text
      @return: the text with dollars replaced, or raise
          HasExprException if there are interpolated expressions
      """
  
      def _sub(m):
          if m.group(0) == '$$':
              return '$'
  
          raise HasExprException()
  
      return _dollar_strip_re.sub(_sub, text)