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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 _findUniqueMappingKeys(mapping):
 """Find mapping keys that only have one entry (value length of 1. :param mapping: dict, for each key contains a set of entries :returns: a set of unique mapping keys """


    uniqueMappingKeys = set()
    for key, entries in viewitems(mapping):
        if len(entries) == 1:
            uniqueMappingKeys.add(key)
    return uniqueMappingKeys