code: public function makeHandler($ident)
  	{
  		if (!isset($this->factories[$ident])) {
  			throw new \InvalidArgumentException("Unknown session handler: $ident");
  		}
  
  		return $this->factories[$ident]();
  	}
docs: Make a handler.
  
  @param  string $ident
  
  @return \SessionHandlerInterface
  
  @throws \InvalidArgumentException If ident is invalid