isBetween method
Returns true if the number is between min and max (inclusive).
Example:
5.isBetween(1, 10); // true
5.isBetween(10, 20); // false
Implementation
bool isBetween(int min, int max) {
assert(min <= max, 'min must be less than or equal to max');
return this >= min && this <= max;
}