concatSigCompact function
Implementation
String concatSigCompact(Uint8List r, Uint8List s) {
var rSig = fromSigned(r);
var sSig = fromSigned(s);
var rStr = _padWithZeroes(dynamicToString(toUnsigned(rSig)), 64);
var sStr = _padWithZeroes(dynamicToString(toUnsigned(sSig)), 64);
return dynamicToHex(rStr + sStr);
}