'Initialize the KeyRangeItemGenerator.
Args:
request_manager: A RequestManager instance.
kinds: The kind of entities being transferred, or a list of kinds.
progress_queue: A queue used for tracking progress information.
progress_generator: A generator of prior progress information, or None
if there is no prior status.
key_range_item_factory: A factory to produce KeyRangeItems.'

def __init__(self, request_manager, kinds, progress_queue, progress_generator, key_range_item_factory):

    self.request_manager = request_manager
    if isinstance(kinds, basestring):
        self.kinds = [kinds]
    else:
        self.kinds = kinds
    self.row_count = 0
    self.xfer_count = 0
    self.progress_queue = progress_queue
    self.progress_generator = progress_generator
    self.key_range_item_factory = key_range_item_factory
