public function addReplacements( array $replacements ) : VfsHandler
   {

      foreach ( $replacements as $name => $value )
      {

         if ( null === $value )
         {
            unset( $this->_replacements[ $name ] );
            continue;
         }

         $this->_replacements[ $name ] = $value;

      }

      return $this;

   }