> Does it also need to include `isNullCall` and `isMissingCall` as `partiql-lang-kotlin` [implements](https://github.com/partiql/partiql-lang-kotlin/blob/da22cf8665e1dcf0b3747452285cca6df73c0e95/partiql-spi/src/main/kotlin/org/partiql/spi/function/Function.kt#L28-L29)? _Originally posted by @am357 in https://github.com/partiql/partiql-lang-rust/pull/496#discussion_r1783620523_