docs: public static CalligraphyTypefaceSpan getSpan(final Typeface typeface) {
          if (typeface == null) return null;
          synchronized (sCachedSpans) {
              if (!sCachedSpans.containsKey(typeface)) {
                  final CalligraphyTypefaceSpan span = new CalligraphyTypefaceSpan(typeface);
                  sCachedSpans.put(typeface, span);
                  return span;
              }
              return sCachedSpans.get(typeface);
          }
      }