the 3rd parameter to the operand spec in the %^operator declaration is for subsubops. This is self delimiting, but it is not easy. So currently you have to provide a character that is not in the total subsubop spec, and finish the spec with that character. This should be fixed. A better regex library will do. See https://stackoverflow.com/questions/15253054/regex-matching-closing-bracket-not-in-quotes which uses stuff that python re doesn't support.
the 3rd parameter to the operand spec in the %^operator declaration is for subsubops. This is self delimiting, but it is not easy. So currently you have to provide a character that is not in the total subsubop spec, and finish the spec with that character. This should be fixed. A better regex library will do. See https://stackoverflow.com/questions/15253054/regex-matching-closing-bracket-not-in-quotes which uses stuff that python re doesn't support.