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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 table_as_df(self, table_name):
 """Return a table as a dataframe."""

        self.table_must_exist(table_name)
        query = "SELECT * FROM `%s`" % table_name.lower()
        return pandas.read_sql(query, self.own_conn)