static DoubleRange growRange(DoubleRange r, double amount) {
  ret r == null ?: doubleRange(r.start-amount, r.end+amount);
}

static DoubleRange growRange(double amount, DoubleRange r) {
  ret growRange(r, amount);
}

static IntRange growRange(IntRange r, int amount) {
  ret r == null ?: intRange(r.start-amount, r.end+amount);
}

static IntRange growRange(int amount, IntRange r) {
  ret growRange(r, amount);
}