readVarInt method
Implementation
BigInt readVarInt() {
final first = readUInt8();
if (first < 0xfd) {
// 8 bit
return BigInt.from(first);
} else if (first == 0xfd) {
// 16 bit
return BigInt.from(readUInt16());
} else if (first == 0xfe) {
// 32 bit
return BigInt.from(readUInt32());
} else {
// 64 bit
return readUInt64();
}
}