## Changes
The nil value is a real valid value that we need to represent. To
accommodate this we introduced `dyn.KindInvalid` as the zero-value for
`dyn.Kind` (see #904), but did not yet update the comments on
`dyn.NilValue` or add tests for `kind.go`.
This also moves `KindNil` to be last in the definition order (least
likely to care about it).
## Tests
Tests pass.
Pieter Noordhuis