private Integer getNbSugarsFromInstruction(String instruction) {
        Integer nbSugars = null;

        if (instruction == null || instruction.isEmpty()) {
            nbSugars = 0;
        } else if (instruction.matches("[0-9]+")) {
            try {
                nbSugars = Integer.parseInt(instruction);
                if (nbSugars < 0 || nbSugars > 2) {
                    System.err.println("Can only have [0-2] sugars. Here: " + instruction);
                    nbSugars = null;
                }
            } catch (NumberFormatException e) {
                System.err.println("Cannot parse int: " + instruction);
            }
        }
        return nbSugars;
    }