This disallows LF and CRLF, but seems like it wouldn't disallow CR. It should just be `'//' ~[\r\n]*`. Also, should it consume the trailing newline? The sample comment rule on [this documentation page](https://theantlrguy.atlassian.net/wiki/display/ANTLR4/Lexer+Rules), does. That would make it `'//' ~[\r\n]* '\r'? '\n'`