Rob Earhart suggested the following fix for the grammar:
[...]
As written, the grammar has a shift/reduce conflict related to the way
tests are handled. Here's an example of the ambiguity:
anyof allof true
[...]
I'd solve this by removing "test" as a possible "argument", and putting
an optional "test" into the rule for "command", just before the block /
";". I think this still fits with all the existing commands, and makes
the system as a whole cleaner. [...]
Unfortunately, this doesn't work. A "not" takes a test as an
argument, and this would prevent that.
Larry