get_available_name(name, max_length=None)
Returns a filename that is available in the storage mechanism, possibly taking the provided filename into account. The name argument passed to this method will have already cleaned to a filename valid for the storage system, according to the get_valid_name() method described above.
The length of the filename will not exceed max_length, if provided. If a free unique filename cannot be found, a SuspiciousFileOperation exception is raised.
If a file wit