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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 _join_keys_v1(left, right):
 """ Join two keys into a format separable by using _split_keys_v1. """

    if left.endswith(':') or '::' in left:
        raise ValueError("Can't join a left string ending in ':' or containing '::'")
    return u"{}::{}".format(_encode_v1(left), _encode_v1(right))