# Constants
FeatureClusteredIndex is the `clustered_index` feature.
FeatureIDAutoIDCache is the `auto_id_cache` feature.
FeatureIDAutoRandom is the `auto_random` feature.
FeatureIDAutoRandomBase is the `auto_random_base` feature.
# Structs
ParamMarkerExpr expression holds a place for another expression.
ValueExpr is the simple value expression.