code: protected function cacheMarkers(string $marker): void
      {
          $this->marked[$marker] = [];
          
          foreach ($this->definitions as $definition) {
              foreach ((array) $definition->markers as $m) {
                  if ($m instanceof $marker) {
                      $this->marked[$marker][] = [
                          $definition,
                          $m
                      ];
                  }
              }
          }
      }
docs: Cache all bindings marked with the given marker for faster lookups.
  
  @param string $marker Fully-qualified name of the marker class.