File.open() documentation is incomplete

[sgrekhov]

Please see https://api.dartlang.org/stable/1.24.2/dart-io/File/open.html

Files can be opened in three modes:

FileMode.READ: open the file for reading.

FileMode.WRITE: open the file for both reading and writing and truncate the file to length zero. If the file does not exist the file is created.

FileMode.APPEND: same as FileMode.WRITE except that the file is not truncated.

In fact file can also be opened in FileMode.WRITE_ONLY and FileMode.WRITE_ONLY_APPEND modes
The same is true for File.openSync() and File.openWrite() documentation