code: public function getMarked(string $marker): array
      {
          if (!\is_subclass_of($marker, Marker::class)) {
              throw new \InvalidArgumentException(\sprintf('Marker implementation %s must extend %s', $marker, Marker::class));
          }
          
          if (!isset($this->marked[$marker])) {
              $this->cacheMarkers($marker);
          }
          
          return \array_map(function (array $marked) {
              return $this->shared[$marked[0]->typeName] ?? $this->get($marked[0]->typeName);
          }, $this->marked[$marker]);
      }
docs: Get all objects marked with the given marker.
  
  @param string $marker Fully-qualified name of a marker class.
  @return array All instantiated marked objects.
  
  @throws \InvalidArgumentException When an invalid marker is passed.