<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def start_transfer(self, relation_name):
 """Write records to the data source indicating that a transfer has been started for a particular relation. """

    self.reset(relation_name)
    relation = Relation(name=relation_name)
    self.data_access.insert_model(relation)
    return relation