This method overrides django.core.files.uploadhandler.FileUploadHandler.file_complete.
Subclasses should return a valid ``UploadedFile`` object.
This method overrides django.core.files.uploadhandler.FileUploadHandler.new_file.
This method overrides django.core.files.uploadhandler.FileUploadHandler.receive_data_chunk.
This method overrides django.core.files.uploadhandler.FileUploadHandler.upload_interrupted.