Consider rephrasing "valid" as an algorithm

[annevk]

Currently we have statements such as:

The |config| has either an {{SanitizerConfig/elements}} or a {{SanitizerConfig/removeElements}} key, but not both.

I think it would be clearer if we rewrote this and similar conditions to:

If |config|["{{SanitizerConfig/elements}}"] exists and |config|["{{SanitizerConfig/removeElements}}"] exists, then return false.

[evilpie]

I totally agree. Even writing these assertion statements is awkward.