The File.PrepareStatus enumerated type defines the state of the file in preparation for download.
UNPREPARED : The file hasn’t been requested for preparation.
PREPARE_REQUESTED : A prepare has been requested, however the server hasn’t started the preparation yet.
PREPARING : A prepare has been requested and the file is in the process of being prepared.
PREPARED : Prepare succeeded. The file is ready for download.
ERROR : Prepare failed.
Enumeration: UNPREPARED, PREPARE_REQUESTED, PREPARING, PREPARED, ERROR,