code: decoration of histogram

svg.cpp

@@ -10,9 +10,11 @@ svg_text(double left, double baseline, string text) {
     cout << "<text x='" << left << "' y='" << baseline << "'>" << text << "</text>";
 }
     
-void
-svg_rect(double x, double y, double width, double height) {
-    cout << "<rect x='" << x << "' y='" << y << "' width='" << width << "' height='" << height << "' />\n";
+void svg_rect(double x, double y, double width, double height, string stroke = "black", string fill = "black")
+{
+    cout << "<rect x='" << x << "' y='" << y << "' width='" <<
+        width << "' height='" << height << "' fill='" << fill <<
+        "' stroke='" << stroke <<"' />\n";
 }
 
 void