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  {"pid": 0, "tid": 0, "ph": "B", "name": "beta", "ts": 1},
  {"pid": 0, "tid": 0, "ph": "X", "name": "gamma", "ts": 2, "dur": 5, "args": {"detail": "foobar"}},
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  {"pid": 0, "tid": 0, "ph": "E", "name": "beta", "ts": 13},
  {"pid": 0, "tid": 0, "ph": "E", "name": "alpha", "ts": 14},