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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 scheduling_block_instances(self):
 """Return the a JSON dict encoding the SBIs known to SDP."""

        # TODO(BMo) change this to a pipe?
        sbi_list = SchedulingBlockInstanceList()
        return json.dumps(dict(active=sbi_list.active,
                               completed=sbi_list.completed,
                               aborted=sbi_list.aborted))