Uses a load of indexes:
- equivalent_entities_groups_index
- equivalent_entities_groups_index_r
- disease_hierarchy_distance_index
- disease_hierarchy_index
- rev_disease_hierarchy_distance_index
- node_index
- node_index_r
- source_index
- source_index_r
- rel_type_index
- rel_type_index_r
Also contains find_closest_efo which is useful for searching for disease indications in ontologies.