code: public function setSource($source = '')
      {
          if(!$this->isValid($source)) {
              throw new InvalidSourceExtensionException();
          }
  
          $this->source = $source;
  
          return $this;
      }
docs: Sets source of the .swf file
  
  @param string $source
  @throws Swf\Exception\InvalidSourceExtensionException
  @return $this;