'Initialize the UploadWorkItem instance.
Args:
request_manager: A RequestManager instance.
progress_queue: A queue used for tracking progress information.
rows: A list of pairs of a line number and a list of column values.
key_start: The (numeric) starting key, inclusive.
key_end: The (numeric) ending key, inclusive.
progress_key: If this UploadWorkItem represents state from a prior run,
then this will be the key within the progress database.'

def __init__(self, request_manager, progress_queue, rows, key_start, key_end, progress_key=None):

    _WorkItem.__init__(self, progress_queue, key_start, key_end, ImportStateName, state=STATE_READ, progress_key=progress_key)
    assert isinstance(key_start, (int, long))
    assert isinstance(key_end, (int, long))
    assert (key_start <= key_end)
    self.request_manager = request_manager
    self.rows = rows
    self.content = None
    self.count = len(rows)
