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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 build_from_table(self):
 """ Generates the sql for the FROM portion of the query :return: the FROM portion of the query :rtype: str """

        table_parts = []

        # get the table sql for each table
        for table in self.tables:
            sql = table.get_sql()
            if len(sql):
                table_parts.append(sql)

        # combine all table sql separated by a comma
        sql = 'FROM {0} '.format(', '.join(table_parts))

        return sql