Delete specified file.
			Pass file_etag to avoid race conditions (raises error 412).

def delete_file(self, file_id, file_etag=None):
		'''Delete specified file.
			Pass file_etag to avoid race conditions (raises error 412).'''
		return self( join('files', bytes(file_id)), method='delete',
			headers={'If-Match': file_etag} if file_etag else dict() )