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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 _all_expander(fringe, iteration, viewer):
    '''
    Expander that expands all nodes on the fringe.
    '''
    expanded_neighbors = [node.expand(local_search=True)
                          for node in fringe]

    if viewer:
        viewer.event('expanded', list(fringe), expanded_neighbors)

    list(map(fringe.extend, expanded_neighbors))