public function setAxisLabel( $axis, $label )
	{
	    if ( in_array( $axis, array( 'x', 'y', 'z' ) ) ) {
	        $originalAxisOptions = $this->jsWriter->getOption( 'axes', array() );
	        $desiredAxisOptions = array( "{$axis}axis" => array( 'label' => $label ) );
	        $this->jsWriter->setOption( 'axes', array_merge_recursive( $originalAxisOptions, $desiredAxisOptions ) );
	    } 

		return $this;
	}