Check that we are actually doing an atomic-valid direct step into the inheritance hierarchy (i.e. we are making
a direct move move from parent_type using the a_parent_edge path to reach Current.
(As the canonical_type_mark is selected nearly randomly by the compilation
process, the start_position of the canonical_type_mark itself is not meaningful.)
Check that we are actually doing an atomic-valid direct step into the inheritance hierarchy (i.e. we are making
a direct move move from parent_type using the a_parent_edge path to reach Current.