def METHOD_NAME(s):
    r"""Generator for the set of single pair matchings.
    Args:
        s (tuple): an input tuple
    Returns:
        generator: the set of single pair matching of the tuple s
    """
    def clone_if_single(x):
        """Given an tuple, if its length is one returns a tuple with
        it first and only entry repeated twice. Otherwise it returns the same object.
        """
        if len(x) == 1:
            return (x[0], x[0])
        return x
    for p in partitions(s):
        yield tuple(clone_if_single(i) for i in p)