Mine a new block on the chain.  Header parameters for the new block can be
    overridden using keyword arguments.

def mine_block(chain: MiningChain, **kwargs: Any) -> MiningChain:
    """
    Mine a new block on the chain.  Header parameters for the new block can be
    overridden using keyword arguments.

    """
    if not isinstance(chain, MiningChain):
        raise ValidationError('`mine_block` may only be used on MiningChain instances')
    chain.mine_block(**kwargs)
    return chain