# File lib/yaml/stringio.rb, line 21
        def readline(rs=$/)
            if @eof
                raise EOFError
            else
                if p = @string[@pos..-1]=~rs
                    line = @string[@pos,p+1]
                else
                    line = @string[@pos..-1]
                end
                @pos+=line.size
                @eof =true if @pos==@string.size
                $_ = line
            end
        end