original_string: public function setContentId($cid = null)
      {
          if (!is_null($id = $this->getContentId())) {
              return $id;
          }
  
          $this->_headers->addHeaderOb(
              is_null($cid)
                  ? Horde_Mime_Headers_ContentId::create()
                  : new Horde_Mime_Headers_ContentId(null, $cid)
          );
  
          return $this->getContentId();
      }
code: public function setContentId($cid = null)
      {
          if (!is_null($id = $this->getContentId())) {
              return $id;
          }
  
          $this->_headers->addHeaderOb(
              is_null($cid)
                  ? Horde_Mime_Headers_ContentId::create()
                  : new Horde_Mime_Headers_ContentId(null, $cid)
          );
  
          return $this->getContentId();
      }
code_tokens: public function setContentId ( $ cid = null ) { if ( ! is_null ( $ id = $ this -> getContentId ( ) ) ) { return $ id ; } $ this -> _headers -> addHeaderOb ( is_null ( $ cid ) ? Horde_Mime_Headers_ContentId :: create ( ) : new Horde_Mime_Headers_ContentId ( null , $ cid ) ) ; return $ this -> getContentId ( ) ; }
docstring: Sets the Content-ID header for this part.
  
  @param string $cid  Use this CID (if not already set). Else, generate
  a random CID.
  
  @return string  The Content-ID for this part.
docstring_tokens: Sets the Content - ID header for this part .