src/Ciconia/Ciconia.php
public function addExtension(ExtensionInterface $extension)
    {
        $this->extensions->set($extension->getName(), $extension);

        return $this;
    }
public function addExtension(ExtensionInterface $extension)
    {
        $this->extensions->set($extension->getName(), $extension);

        return $this;
    }
@param ExtensionInterface $extension

@return Ciconia