[type]
Parser

[grammar]
grammar T;
a : 'a' x=('b'|'c') {<Append("\"conjured=\"","$x"):writeln()>} 'd' ;

[start]
a

[input]
ad

[output]
"""conjured=[@-1,-1:-1='<missing 'b'>',<2>,1:1]
"""

[errors]
"""line 1:1 missing {'b', 'c'} at 'd'
"""