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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 create(self, sql=None):
 """CREATE this DATABASE. @param sql: (Optional) A string of psql (such as might be generated by pg_dump); it will be executed by psql(1) after creating the database. @type sql: str @rtype: None """

        create_sql = 'CREATE DATABASE {self.db_name} WITH OWNER {self.user}'
        create_sql = create_sql.format(**vars())
        self.super_psql(['-c', create_sql])
        if sql:
            self.psql_string(sql)