toFixed method
Implementation
String toFixed(BigInt x) {
bool isNegative = x < BigInt.zero;
x = x.abs();
BigInt base = BigInt.from(10).pow(4);
String mod = (x % base).toString();
String m = (x ~/ base).toString();
// 0-pad
while (mod.length % 4 != 0) {
mod = '0' + mod;
}
return '${isNegative ? '-' : ''}$m.$mod';
}