# File lib/math_ml/latex.rb, line 131
                        def scan_option
                                return nil unless scan(/\[/)
                                opt = "["
                                p = pos-1
                                until (s=scan_any(true)) =~ /\A#{RE::SPACE}*\]\z/
                                        opt << s
                                        if eos?
                                                self.pos = p
                                                raise OptionNotClosed
                                        end
                                end
                                opt << s
                                self.pos = p
                                _scan(/\A\[(#{Regexp.escape(opt[RE::OPTION, 1].to_s)})\]/)
                        end