private void removeLeadingZeros() {
            while (input.length() > 0 && input.charAt(0) == '0')
                input.deleteCharAt(0);
        }
Encapsulates the digit input logic and text to duration conversion logic.
android/third_party/time-duration-picker/src/main/java/mobi/upod/timedurationpicker/TimeDurationPicker.java