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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 _check_samples_nodups(fnames):
 """Ensure a set of input VCFs do not have duplicate samples. """

    counts = defaultdict(int)
    for f in fnames:
        for s in get_samples(f):
            counts[s] += 1
    duplicates = [s for s, c in counts.items() if c > 1]
    if duplicates:
        raise ValueError("Duplicate samples found in inputs %s: %s" % (duplicates, fnames))