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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 total_build_duration_for_chain(self, build_chain_id):
 """Returns the total duration for one specific build chain run"""

        return sum([
            int(self.__build_duration_for_id(id))
            for id in self.__build_ids_of_chain(build_chain_id)
        ])