Using merge with unhashable type TimeSeries problematic

[vlsd]

Try the following:

ts_a = traces.TimeSeries(default=traces.Histogram({0:1}))
ts_b = traces.TimeSeries(default=traces.Histogram({0:1}))
traces.TimeSeries.merge([ts_a, ts_b])

and it will result in

/traces/traces/timeseries.py in merge(cls, ts_list, compact, operation, default)
    681
    682         if default is None:
--> 683             unique_defaults = set(ts._default for ts in ts_list)
    684             default = unique_defaults.pop()
    685             if unique_defaults:

TypeError: unhashable type: 'Histogram'

Do the following instead, and it will work:

traces.TimeSeries.merge([ts_a, ts_b], default=traces.Histogram())