readByte method Null safety
Reads a byte from the file.
Returns a Future<int> that completes with the byte,
or with -1 if end-of-file has been reached.
Implementation
Future<int> readByte();Reads a byte from the file.
Returns a Future<int> that completes with the byte,
or with -1 if end-of-file has been reached.
Future<int> readByte();