code: public function firstkey() {
  		$this->keyIterPos = 4;
  
  		if ( !$this->keyIterStop ) {
  			$pos = INF;
  			for ( $i = 0; $i < 2048; $i += 8 ) {
  				$pos = min( $this->readInt31( $i ), $pos );
  			}
  			$this->keyIterStop = $pos;
  		}
  
  		$this->keyIterPos = 2048;
  		return $this->nextkey();
  	}
docs: Get the first key from the CDB file and reset the key iterator.
  
  @return string|bool Key, or false if no keys in file.