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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 _combine_to_jointcaller(processed):
 """Add joint calling information to variants, while collapsing independent regions. """

    by_vrn_file = collections.OrderedDict()
    for data in (x[0] for x in processed):
        key = (tz.get_in(("config", "algorithm", "jointcaller"), data), data["vrn_file"])
        if key not in by_vrn_file:
            by_vrn_file[key] = []
        by_vrn_file[key].append(data)
    out = []
    for grouped_data in by_vrn_file.values():
        cur = grouped_data[0]
        out.append([cur])
    return out