Sort a list of lists with a custom compare function

Also, your compare function is incorrect. It needs to return -1, 0, or 1, not a boolean as you have it. The correct compare function would be:

def compare(item1, item2):
    if fitness(item1) < fitness(item2):
        return -1
    elif fitness(item1) > fitness(item2):
        return 1
    else:
        return 0

# Calling
list.sort(key=compare)

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