Compose callback for alphabet::InitialSymbol tag not registered.
echo "( ( x + z x* + y* x ) ( x + y )* + ( #E + z* y ) x )*" | ./aconvert2 --regexp_from_string | ./acast2 -t UnboundedRegExp | ./aconversions2 -t rg | ./aconvert2 --grammar_to_stringecho "( ( x + z x* + y* x ) ( x + y )* + ( #E + z* y ) x )*" | ./aconvert2 --regexp_from_string | ./acast2 -t UnboundedRegExp | ./aconversions2 -t rg | ./aconvert2 --grammar_to_string