public function set_yaxis(chart_axis $axis, $index = 0) {
        $this->validate_axis('y', $axis, $index);
        return $this->yaxes[$index] = $axis;
    }
public function set_yaxis(chart_axis $axis, $index = 0) {
        $this->validate_axis('y', $axis, $index);
        return $this->yaxes[$index] = $axis;
    }
public function set_yaxis ( chart_axis $ axis , $ index = 0 ) { $ this -> validate_axis ( 'y' , $ axis , $ index ) ; return $ this -> yaxes [ $ index ] = $ axis ; }
Set an Y axis.

Note that this will override any predefined axis without warning.

@param chart_axis $axis The axis.
@param int $index The index of the axis.
Set an Y axis .