mixed readline_info ([string varname [, string newvalue]])
If called with no parameters, this function returns an array of values for all the setting readline uses. The elements will be indexed by the following values: done, end, erase_empty_line, library_version, line_buffer, mark, pending_input, point, prompt, readline_name, and terminal_name.
If called with one parameter, the value of that setting is returned. If called with two parameters, the setting will be changed to the given value.