'Constructor.
Args:
import_record_iterator: Method which yields neutral dictionaries.
dict_to_entity: Method dict_to_entity(input_dict) returns model or entity
instance(s).
name: Name to register with the bulkloader importers (as \'kind\').
reserve_keys: Method ReserveKeys(keys) which will advance the id
sequence in the datastore beyond each key.id(). Can be None.'

def __init__(self, import_record_iterator, dict_to_entity, name, reserve_keys):

    self.import_record_iterator = import_record_iterator
    self.dict_to_entity = dict_to_entity
    self.kind = name
    self.bulkload_state = BulkloadState()
    self.reserve_keys = reserve_keys
    self.keys_to_reserve = []
