In Metamodel::DefiniteHOW§

See primary documentation in context for method type check

method type_check($definite_type$checkee)

Performs a type-check of a definite type against $checkee. This will check if $checkee is of its base type, returning True if they match or False otherwise. This metamethod can get called when a definite type is on the left-hand side of a smartmatch, for instance.