valueTotal method
Get total value of list of num (int/double)
获取num列表的总值(int/double)
Example: 1,2,3,4 => 10
Implementation
num valueTotal() {
num total = 0;
if (this == null || this.isEmpty) return total;
if (this[0] is num) for (var v in this) total += v;
throw FormatException('Can only accepting list of num (int/double)');
}