code: def adjust_properties (self, prop_set):
          
          assert isinstance(prop_set, property_set.PropertySet)
          s = self.targets () [0].creating_subvariant ()
  
          return prop_set.add_raw (s.implicit_includes ('include', 'H'))
docs: For all virtual targets for the same dependency graph as self,
              i.e. which belong to the same main target, add their directories
              to include path.