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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 decref_dependencies(self, term, refcounts):
 """ Decrement in-edges for ``term`` after computation. Parameters term : zipline.pipeline.Term The term whose parents should be decref'ed. refcounts : dict[Term -> int] Dictionary of refcounts. Return ------ garbage : set[Term] Terms whose refcounts hit zero after decrefing. """

        garbage = set()
        # Edges are tuple of (from, to).
        for parent, _ in self.graph.in_edges([term]):
            refcounts[parent] -= 1
            # No one else depends on this term. Remove it from the
            # workspace to conserve memory.
            if refcounts[parent] == 0:
                garbage.add(parent)
        return garbage