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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def is_transfer_complete(self, relation_name):
 """Checks to see if a tansfer has been completed."""

    phold = self.data_access.sql_writer.to_placeholder()
    return self.data_access.find_model(
      Relation,
      ("name = {0} and completed_at is not null".format(phold), [relation_name])) is not None