code: public void appendAttribute(final Appendable appendable,
                                  final CharSequence attrName, final CharSequence attrValue) throws IOException {
  		appendable.append(' ').append(attrName).append("=\"").append(attrValue)
  				.append('"');
  	}
docs: Append a space, then a new element to the appendable element, the name of the element is
  attrName and the value is attrValue. The value won't be escaped.
  
  @param appendable where to write
  @param attrName   the name of the attribute
  @param attrValue  escaped attribute
  @throws IOException If an I/O error occurs