Checkpoint: the blend machine

A smoothie menu is a list of ingredient codes like "ab2x" — digits mark add-in counts. Compute the **total add-in count**: the sum of every digit character's numeric value across the whole menu. Implement process(java.util.ArrayList<String> menu) (0 for empty menu or no digits). Example: ["ab2x", "3"] → 2 + 3 = 5.