^title FileFlags Class
Contains constants for the various file flags used to open or create a file.
These correspond directly to the flags that can be passed to the POSIX
[`open()`][open] syscall.
[open]: http://linux.die.net/man/2/open
They are integers and can be bitwise or'ed together to produce a composite
flag.
## Static Methods
### FileFlags.**readOnly**
The file can be read from but not written. Equivalent to `O_RDONLY`.
### FileFlags.**writeOnly**
The file can be written but not read from. Equivalent to `O_WRONLY`.
### FileFlags.**readWrite**
The file can be both read from and written to. Equivalent to `O_RDWR`.
### FileFlags.**sync**
Writes will block until the data has been physically written to the underling
hardware. This does *not* affect whether or the file API is synchronous. File
operations are always asynchronous in Wren and may allow other scheduled fibers
to run.
This is a lower-level flag that ensures that when a write completes, it has
been flushed all the way to disc.
### FileFlags.**create**
Creates a new file if a file at the given path does not already exist.
### FileFlags.**truncate**
If the file already exists and can be written to, its previous contents are
discarded.
### FileFlags.**exclusive**
Ensures that a new file must be created. If a file already exists at the given
path, this flag will cause the operation to fail.