1("(" @open ")" @close)
 2("[" @open "]" @close)
 3("[|" @open "|]" @close)
 4("{" @open "}" @close)
 5("<" @open ">" @close)
 6("\"" @open "\"" @close)
 7
 8("begin" @open "end" @close)
 9("struct" @open "end" @close)
10("sig" @open "end" @close)
11("object" @open "end" @close)
12("do" @open "done" @close)