@Override
        public RuntimeException syntax(String message) {
            return new RuntimeException("Syntax error at line " + line() + " column " + column()
                    + " of EmitEachSelector message template: " + message);
        }
Parses message templates by slicing out literals and scoped attribute selectors.

<p>Two "@" characters in a row (@@) are considered a single "@" because the
first "@" acts as an escape character for the second.
smithy-model/src/main/java/software/amazon/smithy/model/validation/linters/EmitEachSelectorValidator.java