docs: def add_indent_lines(prefix, s):
      """
      :param str prefix:
      :param str s:
      :return: s with prefix indent added to all lines
      :rtype: str
      """
      if not s:
          return prefix
      prefix_len = str_visible_len(prefix)
      lines = s.splitlines(True)
      return "".join([prefix + lines[0]] + [" " * prefix_len + l for l in lines[1:]])