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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 remove_umis(adj_list, cluster, nodes):
    '''removes the specified nodes from the cluster and returns
    the remaining nodes '''

    # list incomprehension: for x in nodes: for node in adj_list[x]: yield node
    nodes_to_remove = set([node
                           for x in nodes
                           for node in adj_list[x]] + nodes)

    return cluster - nodes_to_remove