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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_joins(self):
 """ Generates the sql for the JOIN portion of the query :return: the JOIN portion of the query :rtype: str """

        join_parts = []

        # get the sql for each join object
        for join_item in self.joins:
            join_parts.append(join_item.get_sql())

        # if there are any joins, combine them
        if len(join_parts):
            combined_joins = ' '.join(join_parts)
            return '{0} '.format(combined_joins)
        return ''