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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 _roots_to_targets(self, build_graph, target_roots):
 """Populate the BuildGraph and target list from a set of input TargetRoots."""

    with self._run_tracker.new_workunit(name='parse', labels=[WorkUnitLabel.SETUP]):
      return [
        build_graph.get_target(address)
        for address
        in build_graph.inject_roots_closure(target_roots, self._fail_fast)
      ]