Lark parser directives

Hello,

I happened to be looking at the documentation for Lark and I noticed
that it has some interesting directives related to combining grammars.

  https://lark-parser.readthedocs.io/en/stable/grammar.html#directives

Templates look intersting too. Curiously, the example given simply
implements ++.

                                        Be seeing you,
                                          norm

--
Norm Tovey-Walsh
Saxonica