code: public String getSVGDocument() {
          StringBuilder b = new StringBuilder();
          b.append("<?xml version=\"1.0\"?>\n");
          b.append("<!DOCTYPE svg PUBLIC \"-//W3C//DTD SVG 1.0//EN\" ");
          b.append("\"http://www.w3.org/TR/2001/REC-SVG-20010904/DTD/svg10.dtd\">\n");
          b.append(getSVGElement());
          return b.append("\n").toString();
      }
docs: Returns an SVG document (this contains the content returned by the
  {@link #getSVGElement()} method, prepended with the required document
  header).
  
  @return An SVG document.