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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 is_singlesig_address(addr, blockchain='bitcoin', **blockchain_opts):
 """ Is the given address a single-sig address? """

    if blockchain == 'bitcoin':
        return btc_is_singlesig_address(addr, **blockchain_opts)
    else:
        raise ValueError('Unknown blockchain "{}"'.format(blockchain))