*Note: There is normally no need to call this function because it's already called by [class@ExportProcedure] after the `run()` callback.
*
*Only use this function if the [class@Metadata] passed as argument of a [class@ExportProcedure]'s run method needs to be
written at a specific point of the export, other than its end.*
This function syncs back this's export properties to the metadata's [flags@MetadataSaveFlags] and
writes the metadata to file.
The metadata is only ever written once. If this function has been called explicitly, it will do nothing when called a second time at the end of the `run()` callback.
| this | |
| exported_image |
the image that was actually exported |
| file |
the file |