| @@ -131,9 +131,9 @@ | ||
| 131 | 131 | * Returns the code for a box with whiskers |
| 132 | 132 | */ |
| 133 | 133 | protected function whiskerBox($x, $w, $median, $top, $bottom, |
| 134 | 134 | $wtop, $wbottom, $round, $whisker_width, $whisker_dash, |
| 135 | - $median_width, $median_dash, Colour $median_colour = null) | |
| 135 | + $median_width, $median_dash, ?Colour $median_colour = null) | |
| 136 | 136 | { |
| 137 | 137 | $t = $this->gridY($top); |
| 138 | 138 | $b = $this->gridY($bottom); |
| 139 | 139 | $wt = $this->gridY($wtop); |