(Parsing) Null token for understand grammar
The ability to define a null token in a list of alternatives in
Understand grammar, to match the existing ability to make a word optional
in a phrase definition. For example,
Understand "google for/-- [text] in/on [library computer]" as consulting
it about (with nouns reversed).
which could match "GOOGLE FOO ON COMPUTER" or "GOOGLE FOR FOO ON COMPUTER".
While there are other ways to achieve this effect, by defining new grammar
tokens, allowing "--" would be quicker and more legible.