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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 get_tracer(self):
 """Return a tracer according to the sampling decision."""

        sampled = self.should_sample()

        if sampled:
            self.span_context.trace_options.set_enabled(True)
            return context_tracer.ContextTracer(
                exporter=self.exporter,
                span_context=self.span_context)
        else:
            return noop_tracer.NoopTracer()