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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_table_existed(self, tablename):
 """ Check whether the given table name exists in this database. Return boolean. """

        all_tablenames = self.list_tables()
        tablename = tablename.lower()

        if tablename in all_tablenames:
            return True
        else:
            return False