getUint64 abstract method Null safety
Returns the positive integer represented by the eight bytes starting
at the specified
byteOffset in this object, in unsigned binary
The return value will be between 0 and 264 - 1, inclusive.
byteOffset must be non-negative, and
byteOffset + 8 must be less than or equal to the length of this object.
int getUint64(int byteOffset, [Endian endian = Endian.big]);