Refactoring Discussion

~cpp 
protected Dollars baseCharge() {
  double result = Math.min(lastUsage(),100) * 0.03;
  if (lastUsage() > 100) {
    result += (Math.min (lastUsage(),200) - 100) * 0.05;
  };
  if (lastUsage() > 200) {
    result += (lastUsage() - 200) * 0.07;
  };
  return new Dollars (result);
}


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protected Dollars baseCharge() {
  double result = usageInRange(0, 100) * 0.03;      //--(1)
  result += usageInRange (100,200) - 100) * 0.05;
  result += usageInRange (200, Integer.MAX_VALUE) * 0.07;
  return new Dollars (result);
}

protected int usageInRange(int start, int end) {
  if (lastUsage() > start) return Math.min(lastUsage(),end) - start;
  else return 0;
}