parser: add null let statement test

Signed-off-by: Marc-Antoine Perennou <Marc-Antoine@Perennou.com>
core: add KuList

Signed-off-by: Marc-Antoine Perennou <Marc-Antoine@Perennou.com>
tests: add tests for list

Signed-off-by: Marc-Antoine Perennou <Marc-Antoine@Perennou.com>