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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_new_preorder( self, preorder_hash, lastblock=None ):
 """ Given a preorder hash of a name, determine whether or not it is unseen before. """

        if lastblock is None:
            lastblock = self.lastblock 

        preorder = namedb_get_name_preorder( self.db, preorder_hash, lastblock )
        if preorder is not None:
            return False
        else:
            return True