code: public static CharSequence concat(CharSequence left, CharSequence right) {
  	if (left instanceof Appendable) {
  	    try {
  		((Appendable) left).append(right);
  		return left;
  	    }
  	    catch (IOException e) {}
  	}
  	return new StringBuilder(left).append(right);
      }
docs: concat 2 CharSequences
  
  @param left
  @param right
  @return concated String